Bitcoin glossary
Find a word from the courses. Each definition gives the main idea in 25 words or fewer. Follow the related lesson for context and further detail.
Last reviewed: 13 November 2026
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0–9
51% attack
Also called: majority attack.
An attacker with majority mining power can reorganise recent valid history or censor confirmations, but cannot override unchanged nodes’ validity rules.
A
address
Also called: Bitcoin address, receiving address.
A short code telling a payer’s wallet where to send bitcoin; it encodes a locking script, and knowing it cannot unlock the coins.
Address cluster
Also called: cluster.
A group of addresses an analyst infers belong together, usually by applying transaction-pattern heuristics.
address poisoning
Sending look-alike address entries into a victim’s history so they later copy the wrong destination.
address reuse
Receiving repeatedly at the same address, making payments easier to link publicly and sometimes exposing additional key information.
Address type
A format for a Bitcoin payment destination, such as legacy, native SegWit or Taproot; it does not identify a different currency.
Aezeed
LND’s seed-backup format, usually represented as 24 words, which differs from BIP39.
air gap
Also called: air-gapped.
Keeping signing equipment disconnected from networks and data cables, exchanging information through methods such as QR codes or removable storage.
amortization
Also called: amortisation.
Spreading equipment purchase cost across its expected useful life when estimating profitability.
Anchor output
Also called: anchor outputs.
A small output in some Lightning commitment transactions that can help attach extra fees through a child transaction.
Anonymity set
The possible participants or outputs among which an observer cannot confidently distinguish yours; its size is not a privacy guarantee.
API
Also called: application programming interface.
A defined set of operations through which software components can communicate and use each other’s functions.
Archival node
Also called: full archival node.
A full node retaining old block data after validating it, so that it can serve historical blocks.
ARM64
Also called: AArch64.
Arm’s 64-bit processor architecture, used by many small computers and other devices.
ASIC
Also called: ASIC miner, application-specific integrated circuit.
A chip designed for one job; Bitcoin mining ASICs specialise in repeated SHA-256 calculations.
Assumevalid
Bitcoin Core’s setting allowing signature checks on sufficiently buried, recognised historical blocks to be skipped during initial synchronisation.
Atomic Multi-path Payment
Also called: AMP, Atomic Multi-path Payments.
A Lightning payment method that splits a secret across payment parts, requiring all parts for settlement.
Atomic payment
Also called: atomic.
A payment designed to complete as a whole or fail, rather than let an intermediary keep one side without forwarding the other.
authenticity check
Also called: Genuine Check.
A manufacturer’s verification procedure checking that a device or its software matches what the maker recognises as genuine.
authorized participant
Also called: authorized participants, APs.
An approved firm creating or redeeming large ETF share blocks with the fund under its procedures.
autotuning
Firmware adjusting individual mining chips’ operating settings to balance speed, power use and stability.
avalanche effect
The property that a small change to a hash function’s input produces a very different output.
B
backup
Also called: wallet backup.
Information kept to recover wallet access after device failure; it must match the wallet’s recovery method.
Base fee
The fixed part of a Lightning forwarding fee, charged separately from its amount-dependent part.
base layer
Bitcoin’s blockchain and the rules for its on-chain transactions, distinct from systems built on top.
Base58Check
Also called: Base58 with checksum.
An encoding using a restricted alphabet and checksum, used by older Bitcoin address formats.
batching
Putting several recipients’ payments into one transaction, often reducing average space and fees per recipient.
bearer asset
An asset controlled through possession or spending capability rather than a named account claim; custody and legal ownership are separate questions.
Bech32
An encoding used by version-zero native SegWit addresses, with a checksum designed to detect typing errors.
Bech32m
An updated checksum encoding used by native witness version-one and later addresses, including Taproot.
Binary
Also called: binaries, software binary.
A built program ready to run, rather than the source code from which it was produced.
BIP
Also called: Bitcoin Improvement Proposal.
A numbered document proposing or describing Bitcoin-related changes; publication or a status label does not force adoption.
BIP 48
Also called: BIP48, BIP-48.
A standard arranging key-derivation paths for hierarchical multisig wallets so different devices can use consistent paths.
BIP 77
Also called: BIP77, asynchronous PayJoin.
A PayJoin design allowing wallets to negotiate asynchronously using encrypted messages through a relay, without being online together.
BIP 78
Also called: BIP78.
A PayJoin protocol in which the payer contacts the recipient’s server to negotiate a joint payment.
BIP 329
Also called: BIP329.
A standard format for exporting and importing wallet labels, which may contain sensitive financial information.
BIP32
Also called: BIP-32.
A standard deriving related wallet keys from one seed, organised as a tree.
BIP39
Also called: BIP-39.
A standard turning randomness into recovery words and deriving a seed from those words and an optional passphrase.
BIP39 passphrase
Also called: 25th word.
An extra secret used with BIP39 recovery words to derive wallet keys; a different passphrase produces a different wallet.
BIP44
Also called: BIP-44.
A wallet derivation-path convention for accounts and addresses, commonly used for legacy single-key outputs.
BIP49
Also called: BIP-49.
A derivation-path convention for single-key P2SH-wrapped SegWit wallets.
BIP84
Also called: BIP-84.
A derivation-path convention for native single-key SegWit wallets using P2WPKH outputs.
BIP86
Also called: BIP-86.
A derivation-path convention for single-key Taproot wallets.
Bitcoin Core
Bitcoin full-node software that verifies blocks and transactions, with an optional wallet and interfaces for other applications.
Bitcoin Knots
Also called: Knots.
Node software derived from Bitcoin Core, with its own features and rules; check the release before assuming chain compatibility.
Bitcoin network
Also called: Bitcoin protocol.
A public payment network whose independent nodes check shared rules without one central bookkeeper.
Bitcoin peer
Also called: peer (Bitcoin).
Another Bitcoin node connected to your node to exchange network messages, transactions or blocks.
bitcoin unit
Also called: bitcoin, BTC.
The money recorded by Bitcoin, divisible into 100 million satoshis per bitcoin under current rules.
Bitcoin vault
A spending design intended to constrain withdrawals, often adding a delay or recovery path; proposed designs have different requirements.
BLAKE2b
Also called: BLAKE2.
A cryptographic hash function different from SHA-256; existing Bitcoin nodes reject any block whose proof of work uses it instead.
Blinded path
Also called: route blinding.
A payment path represented without revealing every node in its hidden segment to the payer.
block
A batch of transactions with a header linking it to earlier blocks and carrying proof of work.
Block explorer
A website or program for inspecting public Bitcoin blocks, transactions and addresses; its display is not independent validation.
block header
Also called: header.
The 80-byte block summary containing version, previous-block hash, Merkle root, timestamp, target and nonce.
block height
A block’s position in a chain, counting the genesis block as zero; competing blocks can share the same height.
block reward
The permitted block subsidy plus fees claimed from other transactions in that block.
block subsidy
Also called: subsidy.
The new bitcoin a miner may claim for a block under the issuance schedule, separate from transaction fees.
block template
A proposed block’s selected transactions and other data before proof of work is completed.
Block-filter index
Stored block summaries that let a node answer compact-filter requests from light clients.
blockchain
Also called: Bitcoin blockchain.
A linked history of blocks, each committing to the previous header, that nodes validate and use to track spendable outputs.
Bloom filter
Also called: bloom filters.
A probabilistic filter a light client can send to a server to request potentially relevant transactions, with privacy trade-offs.
Bluetooth
A short-range wireless connection method; what information it carries depends on the device’s design.
BOLT
Also called: Basis of Lightning Technology, BOLTs.
The collection of specifications describing how compatible Lightning implementations communicate, manage channels and route payments.
BOLT 11
Also called: BOLT11, BOLT 11 invoice.
The Lightning invoice format commonly beginning lnbc, containing a payment hash, recipient node identity and expiry.
BOLT 12 offer
Also called: BOLT12, BOLT12 offer.
A reusable Lightning payment description from which a payer requests a fresh invoice, with features including blinded paths.
Bootloader
The software that starts a computer’s operating system when the machine is powered on.
break-even
Also called: break even.
The point where revenue equals the costs included in a calculation, leaving no profit under those assumptions.
broadcast
Also called: broadcasting.
Sending a signed transaction or block to peers so it can be checked and propagated.
brokerage account
Also called: brokerage.
An account through which a broker holds or arranges securities trades for a customer, subject to its rules and risks.
BSMS
Also called: Bitcoin Secure Multisig Setup, BIP129.
A standard for coordinating multisig setup and exchanging the key and wallet configuration information between coordinators and signers.
BTU
Also called: British thermal unit.
A unit of heat energy; BTU per hour measures heating or cooling power, not total energy use.
C
capital gain or loss
Also called: capital gain, capital loss.
The difference between disposal value and an asset’s tax cost, calculated under the applicable tax rules.
Casa Sovereign Recovery
Also called: Sovereign Recovery.
Casa’s recovery procedure using enough user-held keys to meet the signing threshold, plus saved wallet configuration, without Casa’s signing key.
cash ETF creation/redemption
Also called: cash creations and redemptions, cash (fund creations/redemptions).
Creating or redeeming fund shares using cash rather than directly delivering or receiving the underlying bitcoin.
censorship resistance
Seeking payment confirmation without one central operator’s approval; it does not guarantee immediate inclusion by every miner.
Chain analysis
Also called: chain-analysis, blockchain analysis.
Examining public transaction patterns and outside information to infer links between bitcoin activity and people or organisations.
chain code
Additional data used with a key in BIP32 to derive child keys.
change address
A wallet-controlled address used for returning change from a transaction.
Change detection
Also called: change address detection.
Inferring which transaction output returns funds to the sender, potentially extending the sender’s visible transaction trail.
change output
Also called: change, bitcoin change.
An output returning leftover value to the sender’s wallet; inputs are spent whole, and any value left unassigned becomes the transaction fee.
Channel breach
Also called: breach.
Publication of a revoked Lightning commitment transaction, giving the other participant a limited window to claim a penalty.
Channel capacity
The total bitcoin locked in a Lightning channel, shared between its two sides.
Channel database
Also called: channel.db.
LND’s live record of channel state; restoring an outdated copy can expose funds to penalties.
Channel peer
Also called: channel partner.
The other node participating in one of your Lightning channels.
Channel rebalancing
Also called: rebalancing.
Moving liquidity between channel sides or channels so a node can send, receive or route in the needed direction.
Channel reserve
The minimum balance a channel participant must retain rather than spend through the channel.
Checksum
A value calculated from data to help detect changes or errors; a matching checksum alone does not establish who supplied the data.
Circular rebalancing
A payment sent out through one of your channels and back through another, moving liquidity between them.
Clearnet
Ordinary internet connections outside anonymity networks such as Tor, which can expose a participant’s IP address.
clipboard swapping
Also called: clipboard malware, clipboard hijacking.
Malware replacing a copied payment address with an attacker’s address before the user pastes it.
closed-end trust
A trust whose shares may trade above or below holdings’ value when creation and redemption are restricted.
cloud mining
Buying a claim to mining capacity or earnings operated by someone else, adding counterparty risk and often appearing in scams.
Coin control
Choosing which unspent outputs a wallet uses, instead of accepting its automatic selection.
Coin label
Also called: coin labelling, transaction label, label.
A private wallet note recording a coin’s source or purpose; it is not published as part of the Bitcoin transaction.
coinbase maturity
The rule preventing a coinbase output being spent until at least 100 blocks after its creating block.
coinbase transaction
The first transaction in a block, allowing the miner to claim the permitted new subsidy and transaction fees.
CoinJoin
A transaction combining several participants’ inputs and outputs to make ownership links harder to infer, without transferring custody to an organiser.
CoinJoin coordinator
Also called: coordinator (CoinJoin).
Software or an operator organising a joint transaction, while participants check it and sign only their own inputs.
cold wallet
Also called: cold storage.
A wallet arrangement whose spending keys stay off internet-connected devices.
Collaborative custody
A custody arrangement where a service helps hold or use keys, but the required signing threshold determines who can spend.
Commitment transaction
A pre-signed transaction recording a channel split that its holder can publish to close the channel.
Common Criteria assurance level
Also called: EAL5+, EAL6+, Common Criteria.
A Common Criteria grade (EAL1 to EAL7) for how rigorously a product, such as a chip, was evaluated; it doesn’t guarantee wallet safety.
Common-input-ownership heuristic
The assumption that transaction inputs share an owner; collaborative transactions can invalidate that assumption.
Compact block filter
Also called: compact block filters.
A compact summary of a block that helps a light wallet identify blocks that may contain relevant transactions.
companion app
Software preparing payments on a phone or computer and communicating with a hardware wallet, which checks and signs them.
confirmation
The block including a transaction counts as its first confirmation; each later block on that chain adds another.
consensus rules
Also called: consensus rule.
Conditions each full node applies to decide whether transactions and blocks are valid for the chain it follows.
Consolidation
Also called: consolidate, UTXO consolidation.
Spending several outputs into fewer outputs, reducing future input count while publicly linking the combined coins.
Container
Also called: software container.
An isolated application environment sharing a host computer’s operating-system kernel, rather than a separate physical machine.
contango
A futures condition where later contracts cost more than nearer ones, which can impose costs when positions are rolled forward.
Cooperative close
A channel close agreed and signed by both peers, normally settling their balances in one on-chain transaction.
Core Lightning
Also called: CLN, c-lightning.
A Lightning node implementation designed for extension through plugins.
correlation
A measure of how quantities move together; positive correlation does not guarantee they move together on every occasion.
cost basis
The amount treated as an asset’s acquisition cost for calculating a gain or loss; applicable rules depend on the tax system.
counterparty risk
The risk that a person or institution you rely on will fail to deliver what it owes or promises.
covenant
Also called: covenants.
A proposed spending restriction controlling how an output may be spent later, beyond ordinary signature permission.
CPFP
Also called: Child-Pays-For-Parent.
Spending an unconfirmed output in a higher-fee child transaction, encouraging miners to confirm both parent and child together.
CPU
Also called: central processing unit.
A computer’s general-purpose processor, performing many kinds of instructions rather than specialising only in Bitcoin hashing.
current
Also called: amperes, amps.
The rate of electric charge flow, measured in amperes; equipment and wiring limits must not be exceeded.
curtailed energy
Energy a generator could produce but does not, because demand, transmission or operating limits prevent its use.
Custodial mixer
Also called: custodial mixing service.
A service taking custody of coins and later returning different coins, creating theft and privacy risks distinct from non-custodial CoinJoin.
custodial wallet
Also called: custodial account, custodial.
A service account where the provider controls spending keys and owes the user access under its arrangements.
custodian
A person or service holding spending control for someone else, creating dependence on its security, honesty and ability to pay.
D
Database replication
Keeping database changes copied to another system as they happen, rather than relying only on occasional snapshots.
DATUM
A system letting supported miners build block templates locally while submitting work to a compatible pool.
Dead man’s switch
A mechanism triggered when its owner stops checking in, which may release information or initiate a planned recovery process.
Debian
A community-developed free operating system, commonly used as a Linux distribution on servers and personal computers.
Decoy wallet
A separate wallet intended to appear as the holder’s main wallet under coercion, without guaranteeing that an attacker believes it.
demand response
Also called: demand-response.
Adjusting electricity use when requested or rewarded by a grid programme, such as miners reducing demand during busy periods.
deregulated electricity market
Also called: deregulated grid, deregulated electricity markets.
An electricity market where competing suppliers sell power under local rules, rather than one regulated utility setting every retail arrangement.
derivation path
A sequence describing how to derive a particular key from a wallet’s starting secret.
desktop wallet
Wallet software running on a desktop or laptop computer, with security depending on its key storage and signing arrangement.
difficulty
Also called: mining difficulty.
A relative measure of how hard finding a valid block hash is; higher difficulty requires more attempts on average.
difficulty adjustment
Also called: retarget.
The scheduled recalculation of Bitcoin’s mining target every 2,016 blocks to steer average block spacing toward ten minutes.
digital signature
Also called: signature.
Mathematical proof made with a private key for specified data, checked using the corresponding public key.
Disk image
A file representing a disk or filesystem, used to install an operating system onto storage.
distributed ledger
A record maintained across multiple computers; its rules determine how copies are checked and kept consistent.
diversification
Spreading exposure among assets or risks; it can reduce concentration risk without preventing every loss.
dollar-cost averaging
Also called: DCA, dollar cost averaging.
Buying a fixed money amount at regular intervals, regardless of price; it spreads purchase timing without removing loss risk.
double spend
Also called: double-spend, double spending.
Competing attempts to spend the same output; a valid chain cannot accept both uses of that output.
drawdown
A fall from an earlier peak to a later low, describing how far an asset or portfolio declined.
Dual-funded channel
A payment channel to which both peers contribute bitcoin when it is opened.
Duress PIN
An alternative device code triggering a preconfigured response, such as showing a decoy wallet, without guaranteeing protection from coercion.
dust
Also called: dust limit.
An output considered uneconomical under relay-policy calculations; nodes may refuse to relay its creation even though consensus permits it.
Dynamic DNS
Also called: DDNS.
A service updating a fixed domain name when a computer’s public IP address changes.
E
eCash
Also called: Chaumian eCash.
Digital tokens issued by a mint and redeemable for bitcoin; they represent a claim on custody, not an on-chain coin.
ECDSA
The elliptic-curve signature method Bitcoin has used since 2009 and still uses for non-Taproot addresses, including bc1q; Taproot uses Schnorr.
Eclair
ACINQ’s server implementation of Lightning node software.
Economic dust
An output whose spending fee would consume too much of its value at the fee rate being considered.
EH/s
Also called: exahashes per second.
One quintillion hash attempts per second, equal to 1,000 PH/s.
Electrum
An open-source Bitcoin wallet supporting keys, hardware signing, coin control and connections to Electrum servers.
Electrum protocol
The request-and-response interface compatible wallets use to obtain transaction history and broadcast payments through Electrum servers.
Electrum server
Software indexing blockchain transactions by address-related scripts so compatible wallets can query their history.
elliptic curve
A mathematical structure used in Bitcoin signatures, relating private and public keys through operations designed to be hard to reverse.
encryption
Transforming data using a key so its original contents can be recovered only with appropriate decryption information.
entropy
Also called: randomness.
Unpredictability used when generating wallet secrets; more correctly generated random bits mean more possible secrets.
Escrow
Funds held or locked under agreed conditions until a trade completes or a dispute is resolved.
Esplora server
A server offering blockchain data through an HTTP interface; a wallet querying its addresses can reveal them to its operator.
ETF
Also called: exchange-traded fund.
A fund with exchange-traded shares; holding them gives a claim on the fund, not direct control of bitcoin it holds.
ETF creation
Also called: creation.
Issuing new ETF shares in exchange for cash or assets delivered through authorised participants under the fund’s rules.
ETF redemption
Also called: redemption.
Cancelling ETF shares in exchange for cash or assets from the fund, normally through authorised participants.
exchange
A service for buying, selling or exchanging assets; coins left in its custody depend on that service.
exchange-traded note
Also called: ETN, ETNs.
An exchange-traded debt note tracking a stated reference, leaving investors exposed to the issuer’s ability to pay.
exchange-traded product
Also called: ETP, ETPs.
An exchange-traded financial product; the umbrella can include funds and notes with different structures, protections and risks.
Executor
A person appointed to administer a deceased person’s estate and carry out the will under the applicable law.
Exit relay
Also called: Tor exit relay.
The last Tor relay when connecting to an ordinary internet service, which sees that destination but not the original user’s address.
expected value
The probability-weighted average of possible outcomes; it is not a promise about one miner’s short-term income.
expense ratio
Also called: annual fee, fund fee.
A fund’s recurring annual charges as a percentage of assets, reducing the return shareholders retain.
Expired key
Also called: key expiry.
A key past the expiry date in your copy; owners can extend it, so re-import it from the same source and check again.
Ext4
A Linux filesystem format used to organise files and directories on a storage device.
extended public key
Also called: xpub, ypub, zpub.
An account’s public key plus the extra data to calculate all its addresses, but not to spend; whoever holds it sees the account’s history.
extra nonce
Also called: extranonce.
Data varied in the coinbase transaction to create new block candidates and extend the search beyond the header nonce.
F
Federated custody
Custody shared by a group whose required threshold jointly controls withdrawals, rather than one custodian or the user alone.
federation
A designated group jointly operating a system or controlling transfers under a threshold arrangement, rather than open Bitcoin mining.
Fedimint
Software for federations that jointly custody bitcoin and issue blinded eCash claims redeemable through participating clients.
Fedimint federation
A group of guardians jointly operating a Fedimint mint and holding its backing bitcoin under threshold control.
fee bumping
Also called: fee bump.
Increasing the fee incentive for a waiting transaction, using methods such as replacement or a higher-fee child.
fee rate
The transaction fee divided by virtual size, indicating how much the transaction offers per unit of block space.
fee sniping
Trying to replace a recent block to capture its unusually large fees, instead of building on it.
fiat money
Also called: fiat, fiat currency.
Money issued within government and banking systems without a promise of redemption for a fixed quantity of a commodity.
Filesystem
The format and rules an operating system uses to organise files on a storage device.
Firmware
Software built into a device to control its operation; flaws or malicious updates can affect what the device signs.
Force close
Also called: force-close, unilateral close.
A channel close published by one peer without the other’s cooperation, with waiting periods and possibly additional transactions.
FPGA
Also called: field-programmable gate array.
A chip whose logic can be configured after manufacture; miners used it before dedicated ASICs became dominant.
FPPS
Also called: Full Pay Per Share.
A pay-per-share pool method also including an estimated transaction-fee component in share payouts.
Full node
Also called: Bitcoin full node.
Software independently checking Bitcoin blocks and transactions against its consensus rules.
full-disk encryption
Operating-system encryption that keeps a drive unreadable while the computer is switched off; it does not protect data from malware once unlocked.
Funding transaction
An on-chain transaction that locks bitcoin into a Lightning channel’s shared spending conditions.
futures contract
Also called: futures, futures contracts.
A contract setting future delivery or cash settlement terms tied to an asset’s price, rather than direct ownership of the asset.
futures-based bitcoin ETF
Also called: futures-based Bitcoin ETFs, futures bitcoin ETF.
A fund gaining Bitcoin-price exposure through futures contracts rather than holding the corresponding amount of bitcoin directly.
G
gap limit
How many unused addresses a wallet checks ahead when searching for payments; too small a limit can hide later-used addresses.
genesis block
Also called: block 0.
Bitcoin’s first block, built into node software as the chain’s starting point.
GH/s
Also called: gigahashes per second.
One billion hash attempts per second, equal to 1,000 MH/s.
GPG
Also called: GnuPG, GNU Privacy Guard.
Software implementing OpenPGP, used here to check release signatures and manage public signing keys.
GPU
Also called: graphics processing unit.
A processor built for many parallel calculations, historically used for Bitcoin mining before specialised ASICs became dominant.
grid balancing
Coordinating electricity supply and demand to keep the grid stable; interruptible mining demand can be one participant.
gross revenue
Income before deducting expenses such as pool fees, electricity and hardware costs.
Guardian
Also called: Fedimint guardian.
A federation operator holding part of the authority over its bitcoin and participating in eCash issuance and redemption.
H
halving
Also called: Bitcoin halving.
The scheduled reduction of Bitcoin’s per-block subsidy by half every 210,000 blocks, with amounts rounded down to whole satoshis.
hard fork
A rule change allowing blocks earlier rules rejected, so unmodified nodes may follow a different chain.
hardened derivation
Also called: hardened.
A child-key derivation method requiring the parent private key, preventing derivation using only its extended public key.
hardware wallet
Also called: hardware signing device.
A dedicated device designed to keep spending keys separate from an internet-connected computer and sign transactions without exposing those keys to that computer.
hash
A fixed-length result calculated from data, used as a fingerprint for checking changes and linking records.
hash function
Also called: cryptographic hash function, cryptographic hashing.
A calculation mapping data to a fixed-length fingerprint; small input changes produce a different result.
hash rate
Also called: hashrate, hash power, hashing power.
The number of hash attempts per second by a miner or network, commonly measured in TH/s, PH/s or EH/s.
hashboard
A circuit board containing mining chips and their supporting components inside an ASIC miner.
hashprice
Expected gross mining revenue per unit of hash rate per day, before electricity, pool fees and hardware costs.
heat pump
A device moving heat using electricity, often delivering more heating energy than the electrical energy it consumes.
Heuristic
Also called: heuristics.
A useful inference rule that suggests a link without proving it in every case.
hexadecimal
A base-sixteen notation using digits zero through nine and letters a through f, commonly displaying hashes and keys.
hierarchical deterministic wallet
Also called: HD wallet, HD wallets.
A wallet deriving a tree of keys from one starting secret, so compatible software can reproduce them.
HMAC-SHA512
Also called: HMAC-SHA-512.
A keyed hashing method using SHA-512, used in wallet seed and child-key calculations.
Hold invoice
A Lightning invoice whose payment remains conditional until the recipient settles it with the secret or cancels it.
hosting
Also called: mining hosting.
A service running your mining equipment at its facility; you depend on the operator’s custody, charges and performance.
hot wallet
A wallet arrangement keeping spending keys on an internet-connected device.
HTLC
Also called: Hash Time-Locked Contract, Hash Time-Locked Contracts.
A conditional payment unlocked by a matching secret, with a timeout path allowing the payer to reclaim it.
HTTPS
HTTP protected by TLS, encrypting the connection and checking the server’s certificate, rather than proving every downloaded file is safe.
hydro cooling
Also called: liquid cooling, hydro.
Removing mining heat with circulating liquid and external heat-transfer equipment instead of relying only on air.
I
I2P
Also called: Invisible Internet Project.
An anonymity network supporting connections to services and peers inside its own routed network.
immersion cooling
Placing suitable mining equipment in non-conductive liquid that carries heat away; it requires equipment and procedures designed for that system.
in-kind
Also called: in-kind creation, in-kind redemption.
Fund creation or redemption using the underlying asset, such as bitcoin, instead of cash.
Inbound liquidity
Also called: inbound capacity.
Room available on the other side of your Lightning channels for payments coming to you.
index fund
A fund designed to follow a specified market index rather than select investments independently.
inflation
A general rise in prices, reducing what money buys; it differs from Bitcoin’s rate of new issuance.
Inheritance plan
Also called: Bitcoin estate plan.
Instructions and access arrangements allowing chosen people to recover bitcoin after death, without unnecessarily exposing it during life.
Initial Block Download
Also called: IBD, initial sync.
A node’s initial process of obtaining blockchain data and checking it according to its configured validation settings.
input
Also called: transaction input.
A reference to an earlier output being spent, accompanied by information needed to satisfy its spending conditions.
insolvency
Being unable to meet debts or having liabilities exceed assets under the relevant test; either can threaten customer access.
IP address
A numerical network address used to reach a device or connection; it can reveal information about where a connection originates.
IPv4
The version of internet addressing using 32-bit addresses, commonly written as four decimal numbers separated by dots.
IPv6
The version of internet addressing using 128-bit addresses, usually written as groups of hexadecimal digits separated by colons.
issuer
An entity authorised to create or issue a currency or financial claim under its governing rules.
J
joule
Also called: joules.
A unit of energy; mining-efficiency figures often express joules consumed per trillion hash attempts.
joules per terahash
Also called: J/TH.
Joules consumed per trillion hash attempts; a lower figure means less electrical energy for the same amount of hashing.
JSON-RPC
An RPC protocol representing requests and responses as JSON messages.
K
keylogger
Also called: keyloggers.
Software or hardware recording keystrokes, potentially capturing passwords or recovery information typed on the affected machine.
Keyring
A collection of cryptographic keys stored by software such as GPG.
kilowatt-hour
Also called: kWh, kilowatt-hours.
A unit of energy: using one kilowatt of power for one hour consumes one kilowatt-hour.
KYC
Also called: Know Your Customer, identity checks.
Identity checks a service requires from customers, often linking their legal identity with their financial activity.
L
LDK Node
A ready-to-use Lightning node implementation built with Lightning Dev Kit components.
ledger
A record of transactions and ownership or spending claims; Bitcoin’s shared ledger is checked independently by full nodes.
legal tender
A legal status concerning money for settling debts; its effects depend on local law and do not always compel every seller.
liabilities
Amounts or obligations a person or company owes to others; asset holdings alone do not show whether those obligations are covered.
Light client
Also called: light wallet.
Software using limited blockchain data and external peers rather than independently checking every consensus rule.
Lightning address
A human-readable address whose provider supplies Lightning invoices; it is not an on-chain Bitcoin address.
Lightning Dev Kit
Also called: LDK.
A collection of software components developers use to build Lightning wallets and nodes.
Lightning dust limit
Also called: channel dust limit, dust limit (Lightning).
A channel setting below which commitment outputs are omitted; their value contributes to closing fees or anchors instead.
Lightning gateway
A Lightning node connecting a Fedimint federation’s eCash payments with payments on the Lightning Network.
Lightning invoice
Also called: invoice.
A payment request carrying the information a Lightning wallet needs to pay a recipient.
Lightning Network
Also called: Lightning.
A payment network using Bitcoin channels to update balances off-chain, with on-chain transactions opening and settling those channels.
Lightning node
Software maintaining payment channels, handling Lightning payments and watching the blockchain for channel activity.
Lightning service provider
Also called: LSP.
A service helping a Lightning wallet connect, manage channels or obtain liquidity, with fees and privacy trade-offs.
LND
Also called: Lightning Network Daemon.
An implementation of Lightning node software used for channel management, payments, routing and watching for channel breaches.
LNURL
A family of web-based Lightning protocols, often allowing a wallet to request an invoice from a service.
Local balance
Bitcoin assigned to your channel side, distinct from the amount currently available to send after channel rules and restrictions.
Local network
Also called: LAN, local area network.
The network connecting nearby devices, such as computers and a node inside a home.
locking script
Also called: output script, scriptPubKey.
The conditions an output sets for spending its bitcoin, checked when a later transaction tries to use it.
Loop In
An on-chain-to-Lightning swap that adds spendable local balance to a Lightning channel.
Loop Out
A Lightning-to-on-chain swap that spends channel balance and creates room to receive over Lightning.
lump-sum investing
Also called: lump sum.
Investing the planned amount at once instead of spreading purchases over time; the result depends on later price changes.
M
M2
A measure of money including cash, bank deposits and other readily available balances, with components set by the reporting authority.
Maker
Also called: order maker, CoinJoin maker.
A participant posting an offer or providing available liquidity, as opposed to taking an existing offer.
malware
Software designed to harm, spy on, or control a device, including stealing secrets or changing payment details.
Manifest
Also called: checksum manifest.
A published list identifying release files and their checksums, which can itself carry a digital signature.
master fingerprint
Also called: wallet fingerprint.
A short identifier derived from a wallet’s master public key, helping recognise which wallet a descriptor or device refers to.
mempool
A node’s local collection of unconfirmed transactions it accepts and may relay; there is no single global waiting room.
Merkle proof
A path of sibling hashes used to check that a transaction belongs to the tree committed by a block header.
Merkle root
The top hash of a Merkle tree, included in a block header to commit to its transaction list.
Merkle tree
A tree built by hashing transaction hashes in pairs until one root commits to the whole set.
metal backup
Wallet recovery information recorded on durable metal to improve resistance to hazards such as heat and water.
MH/s
Also called: megahashes per second.
One million hash attempts per second.
microcontroller
A small, cheap computer on a single chip; NerdMiner gadgets hash with one, millions of times slower than a mining ASIC.
microprobing
Physically probing tiny chip circuits to observe internal signals, potentially exposing stored secrets.
microSD card
Also called: microSD, SD card.
A small removable flash-storage card, often used to boot a single-board computer.
millisatoshi
Also called: msat, msats, millisatoshis.
One thousandth of a satoshi, used in Lightning accounting; on-chain outputs still use whole satoshis.
miner
A person or operation using computing equipment to compete to propose Bitcoin blocks through proof of work.
miner capitulation
Financially stressed miners selling reserves or stopping operations because expected revenue no longer covers their costs.
miner signalling
Also called: miner signaling, signalling, signaling.
Information in block headers indicating readiness for a proposed change; it does not by itself change another node’s rules.
minimum payout
The smallest unpaid pool balance qualifying for payment; leaving earnings below it means continuing to trust the pool.
mining
Competing to propose Bitcoin blocks by finding header hashes below a target; nodes independently check the resulting blocks.
mining pool
A group coordinating mining work and sharing rewards according to an agreed payout method.
mining profit
Also called: profit.
Mining revenue after counted costs; check whether the calculation also includes hardware, maintenance and taxes.
Miniscript
A structured way to write and analyse Bitcoin spending conditions, helping compatible wallets understand and check them.
monetary debasement
Also called: debasement.
A reduction in money’s purchasing power or integrity, often discussed in relation to expanding supply; demand and economic conditions also matter.
most-work chain
Also called: chain with the most accumulated work.
The valid chain with the most accumulated proof of work; nodes compare it only after applying validity rules.
Multi-path payment
Also called: MPP, multi-path payments.
A Lightning payment split across several routes so their available liquidity can jointly carry its amount.
Multisig
Also called: multisignature, multi-signature, M-of-N.
Spending conditions requiring an agreed number of signatures from a defined set of keys.
Multisig coordinator
Also called: coordinator (multisig).
Wallet software assembling public key information and collecting signatures, without necessarily holding any spending key.
N
native SegWit
A SegWit output used directly rather than wrapped in P2SH; version-zero mainnet addresses begin bc1q.
net asset value
Also called: NAV.
The value of a fund’s assets minus its liabilities, usually expressed per share.
network effects
When a service becomes more useful as more people use or accept it, making established networks harder to replace.
Network layer
The part of communication involving addresses, connections and routing between computers, separate from public transaction contents.
Network port
Also called: port.
A numbered endpoint that directs a network connection to the intended service on a computer.
Network-attached storage
Also called: NAS.
A storage device accessible over a local network, which can hold backups separately from the node.
Neutrino
A Bitcoin light-client implementation that uses compact block filters instead of fully validating the blockchain itself.
NFC
A short-range wireless communication method used by some devices; supported actions depend on the device’s design.
node
A computer participating in a network; its checking, storage and communication roles depend on the software and configuration.
Node ID
Also called: node identity.
The public key identifying a Lightning node, distinct from a Bitcoin receiving address.
Node platform
Also called: node distribution, node operating system.
A package combining Bitcoin node software with management tools and optional apps, simplifying installation and configuration.
non-custodial wallet
Also called: non-custodial, self-custody wallet.
A wallet arrangement where the user, rather than a service, controls the spending keys and necessary recovery information.
Non-KYC
Also called: no-KYC.
Activity without a service collecting formal customer identification; it does not guarantee anonymity or remove other legal obligations.
nonce
A field miners vary in a block header while searching for a hash that meets the target.
Nostr
A messaging protocol using public-key identities and independent relay servers; some Lightning tools use it for connection or tipping.
Nostr relay
A server accepting and distributing signed events for Nostr clients according to the Nostr protocol.
Nunchuk Backup Password
Also called: Backup Password.
A secret decrypting an inheritance key’s stored backup for supported Nunchuk plans; it is distinct from the Magic Phrase.
Nunchuk Magic Phrase
Also called: Magic Phrase.
A phrase identifying a Nunchuk inheritance claim; claiming also requires control of the inheritance key and the plan’s other conditions.
NVMe
Also called: NVM Express.
A protocol for communicating with non-volatile storage, commonly used by fast SSDs.
NWC
Also called: Nostr Wallet Connect.
A protocol letting an app request Lightning-wallet actions through Nostr messages, subject to the wallet’s permissions.
O
off-chain
Occurring outside Bitcoin’s base-layer transaction history, with verification and settlement assumptions depending on the system.
on-chain
Recorded or settled through a transaction in Bitcoin’s blockchain.
Onion routing
Passing a connection or payment through layered encryption so each intermediary learns only the information needed for its next step.
Onion service
Also called: onion services, .onion address.
A service reachable through Tor without publishing its server’s ordinary internet address to connecting users.
OP_RETURN
A script operation used in provably unspendable outputs, often to record data; relay limits and consensus validity differ.
OP_VAULT
Also called: BIP 345, BIP345.
A closed Bitcoin proposal for Script-based vault restrictions; it is not an activated protection on Bitcoin.
open source
Also called: open-source.
Software whose licence permits inspecting, using, modifying and sharing its source code under the stated terms.
open-source hardware
Hardware designs published under a licence allowing inspection and reuse; publication alone does not prove a particular device is safe.
OpenPGP
A standard for cryptographic signing and encryption used to verify some software releases.
OpenPGP primary key
The main OpenPGP key to which identity information and specialised subkeys can be attached.
Operational security
Also called: OpSec.
Habits limiting the information and access that could let someone target you, your devices or your bitcoin.
order book
Also called: order books.
A list of standing buy and sell orders on a trading venue, showing offered prices and quantities.
Outbound liquidity
The amount your Lightning channels can currently send, after their spending restrictions and reserved funds.
output
Also called: transaction output.
A transaction entry assigning a bitcoin amount to spending conditions; it can be spent later if its conditions are satisfied.
output descriptor
Also called: wallet descriptor, descriptor, wallet configuration file.
Text describing a wallet’s spending rules and key derivation, used to locate and reconstruct its outputs.
over-the-counter trading
Also called: OTC.
Trading arranged directly between parties or through a dealer rather than through a public exchange order book.
overclocking
Running hardware above standard clock settings, potentially increasing speed, power use, heat and failure risk.
P
P2PKH
Also called: Pay to Public Key Hash, legacy address, Legacy.
A spending format locking an output to a public-key hash, commonly represented by a mainnet address starting with 1.
P2SH
Also called: Pay to Script Hash.
An output type committing to a script whose full spending conditions are revealed when the output is spent.
P2SH-P2WPKH
Also called: Nested SegWit (single-key).
A P2WPKH payment wrapped inside P2SH, using a mainnet address starting with 3 for older wallet compatibility.
P2TR
Also called: Pay to Taproot.
A Taproot output format committing to a public key, spendable through its key path or an optional committed script path.
P2WPKH
Also called: Pay to Witness Public Key Hash.
A version-zero SegWit format paying a public-key hash, commonly using a bc1q address and witness signatures.
P2WSH
Also called: Pay to Witness Script Hash.
A native SegWit output type committing to a spending script, commonly used for multisig wallets.
paper wallet
A private key and its address printed on paper, often as QR codes; an outdated method, unlike writing down recovery words.
Parts per million
Also called: ppm.
A rate measured in millionths; in routing fees, 100 ppm means one sat per 10,000 sats forwarded.
passphrase
A secret phrase; its role varies: it may encrypt a backup, or with BIP39 open a different wallet from the same words.
PayJoin
A payment where payer and recipient contribute inputs to the same transaction, weakening the assumption that all inputs have one owner.
Payment channel
Also called: channel, Lightning channel.
Bitcoin locked under shared spending rules, allowing participants to update how its balance is divided without publishing every payment.
Payment hash
The hash identifying the secret required to settle an HTLC-based Lightning payment.
Payment in flight
Also called: payments in flight.
A Lightning payment with unresolved conditional transfers, whose eventual outcome is not yet settled.
Payment layer
The channel network handling payments between on-chain settlements, rather than publishing each payment as a blockchain transaction.
PBKDF2
A method repeatedly applying a keyed hash to derive secret data from a password or recovery phrase.
peer-to-peer networking
Also called: peer-to-peer, P2P.
Computers communicating directly as peers rather than routing every interaction through one central service.
Peer-to-peer trade
Also called: P2P trade.
A trade between counterparties rather than a purchase from an exchange’s own inventory, possibly coordinated by platform software.
Penalty transaction
Also called: justice transaction.
A transaction claiming a cheating channel peer’s funds after they publish a revoked channel balance.
PH/s
Also called: petahashes per second.
One quadrillion hash attempts per second, equal to 1,000 TH/s.
phishing
Impersonation designed to trick someone into revealing secrets or authorising harmful actions, through messages, websites or fake software.
PIN
Also called: personal identification number.
A device or app access code; it does not protect a copied recovery backup used elsewhere.
point-of-sale mode
Also called: point of sale.
A wallet display or workflow intended to request and receive payments from customers.
Ponzi scheme
Also called: Ponzi.
A fraud paying earlier participants with later deposits rather than genuine earnings, failing when fresh money runs short.
pool fee
A pool’s charge for coordinating mining and payouts, often taken as a percentage of credited earnings.
Port forwarding
A router rule directing incoming connections from the public internet to a particular service on a local device.
power purchase agreement
Also called: PPA.
A contract setting terms for buying electricity, often including price and quantity over an agreed period.
PPLNS
Also called: Pay Per Last N Shares.
A pool method sharing block rewards among a recent window of shares, so payouts depend on actual pool successes.
PPS
Also called: Pay Per Share.
A pool method paying an expected subsidy amount per valid share, transferring block-finding variability to the pool.
PPS+
A pool method paying expected subsidy per share and distributing fees according to blocks the pool actually finds.
Preimage
Also called: payment preimage.
The secret input whose hash matches a payment’s agreed hash; revealing it lets the conditional payment complete.
Primary spending key
Also called: primary key (inheritance).
A key authorised to spend immediately under a wallet’s normal path, unlike a delayed recovery key.
Privacy
Also called: financial privacy.
Control over who can learn about your balances, payments, identity and connections.
Private broadcast
Also called: privatebroadcast.
Sending a transaction through separate, short-lived anonymity-network connections to reduce links to a node’s ordinary peer traffic.
Private channel
Also called: unannounced channel.
A Lightning channel not publicly announced, though its peers and payments can still reveal information about it.
private key
A secret number used to make signatures that satisfy a coin’s spending conditions.
private placement
A securities offering sold privately to eligible investors rather than through a general public share offering.
proof of reserves
Also called: proof-of-reserves.
Evidence of assets a custodian controls at a point in time; it does not by itself prove all customer obligations are covered.
proof of stake
Also called: PoS.
A consensus approach using staked holdings to select or weigh block validators rather than mining work; designs and penalties vary.
proof of work
Also called: PoW, proof-of-work.
Evidence of finding a block-header hash meeting the target; repeated hashing makes producing this evidence costly and checking it straightforward.
prospectus
A fund’s formal disclosure document describing its objective, structure, charges and risks.
protocol
Message formats and rules used by computers to communicate or participate in a system.
Protocol dust
Also called: relay dust threshold, dust threshold.
An output below a node’s configured relay-policy threshold; this is not the smallest amount Bitcoin’s consensus rules can represent.
Proxy
An intermediary through which an application makes network connections.
Pruned node
A full node that checks the chain but deletes older block files to save storage.
PSBT
Also called: Partially Signed Bitcoin Transaction.
A portable transaction format carrying information needed for separate devices or people to add signatures.
Pseudonymity
Also called: pseudonymous.
Using identifiers rather than real names, without guaranteeing that outside information cannot link those identifiers to people.
PSU
Also called: power supply unit.
A power supply converting incoming electricity into the voltage and current needed by mining hardware.
Public channel
A Lightning channel announced to the network so other nodes can discover it for routing.
public key
Information calculated from a private key, used to check signatures without exposing that secret.
Q
QR code
Also called: QR codes.
A machine-readable square pattern encoding data such as an address or invoice; scanning does not prove the content is trustworthy.
quantum computer
A computer using quantum effects for certain calculations; sufficiently capable machines could threaten today’s public-key signature systems.
R
RBF
Also called: Replace-By-Fee.
Replacing an unconfirmed transaction with another spending the same inputs, normally offering a higher fee and subject to node policies.
Recovery key
A key authorised by an alternative recovery spending path, potentially after a specified delay.
Relative timelock
A spending delay measured from when the relevant output was confirmed, rather than from a fixed calendar date.
relay policy
A node’s rules for accepting and forwarding unconfirmed transactions, distinct from consensus rules deciding block validity.
Remixing
Also called: remix.
Putting a previously mixed coin through another mixing round to try to improve its privacy.
Remote balance
The bitcoin on your peer’s side of a channel, which contributes to your ability to receive payments.
replay protection
Rules making a transaction signed for one chain invalid on another, reducing accidental spending across both after a split.
Reproducible build
Also called: reproducible builds.
A build process that lets independent builders produce identical release files from the same source and specified environment.
resistance heater
A heater converting electrical energy directly into heat, unlike a heat pump that moves additional heat from elsewhere.
retirement account
Also called: IRA, retirement accounts.
A legally defined account with retirement-related tax rules; eligibility, withdrawals and tax treatment depend on the jurisdiction and account type.
return on investment
Also called: ROI.
Gain or loss compared with the invested amount over a stated period, including the costs counted.
Revocation key
A channel penalty key whose spending secret becomes available to the peer when an old channel state is revoked.
Revoked key
Also called: key revocation.
A key its owner has marked as no longer valid for future trust, for example after compromise.
RIPEMD-160
Also called: RIPEMD160.
A hash function producing a 160-bit result, used with SHA-256 in several Bitcoin address constructions.
RISC-V
An open instruction-set architecture implemented by different processors; software must support the specific hardware.
RoboSats federation
Independent trade coordinators sharing a RoboSats interface and order discovery, rather than jointly controlling one Fedimint mint.
RoboSats fidelity bond
Also called: fidelity bond (RoboSats).
A refundable trade deposit that can be forfeited when a participant breaks the trading rules.
RoboSats Garage Key
Also called: Garage Key.
A secret deriving and recovering RoboSats trading identities; anyone holding it can access those robots and their active trades.
roll cost
Also called: rolling.
The gain or loss from replacing an expiring futures position with a later one; contango can make replacement costly.
Route hint
Also called: routing hint.
Extra channel information in an invoice that helps a payer reach a recipient through unannounced channels.
Routing
Also called: route.
Finding and using a path of payment channels to reach a Lightning recipient.
Routing fee
Also called: routing fees.
The fee charged by an intermediate Lightning node for forwarding a payment through its channels.
Routing hop
Also called: hop.
One step between neighbouring nodes along a Lightning payment route.
RPC
Also called: remote procedure call.
A way for one program to request operations from another program through a defined interface.
S
S&P 500
An index tracking selected large US publicly traded companies; it is a benchmark, not one company or a Bitcoin rule.
sat/vB
Also called: satoshis per virtual byte.
Satoshis per virtual byte: a fee-rate unit measuring how much a transaction offers per unit of block space.
satoshi
Also called: sat, sats, satoshis.
One hundred-millionth of a bitcoin, the smallest amount unit recorded on Bitcoin’s base layer.
Schnorr signature
Also called: Schnorr.
The signature scheme introduced to Bitcoin with Taproot, enabling efficient checking and useful ways to combine signing arrangements.
Script type
The form of spending conditions and output encoding used by a wallet, affecting addresses and transaction behaviour.
secure element
Also called: SE.
A chip designed to resist physical extraction of secrets; protection depends on the device’s design and implementation.
security budget
The income paying miners to produce proof of work, funded by block subsidies and transaction fees.
Security deposit
Funds committed as protection against a trade participant breaking agreed obligations.
seed
Secret data from which a wallet derives related keys.
seed phrase
Also called: recovery words, recovery phrase, seed words, wallet backup words.
Usually 12, 20 or 24 words backing up wallet keys; anyone with them, and the passphrase if set, can spend what those keys control.
SegWit
Also called: Segregated Witness.
A Bitcoin upgrade separating witness data and changing weight accounting, enabling more efficient spending and later protocol improvements.
self-custody
Controlling the spending keys yourself rather than depending on a service to authorise or release your coins.
SEPA
Also called: Single Euro Payments Area.
An area where participating countries use common standards for euro bank transfers and direct debits.
settlement
Also called: settled.
Completing a payment or trade’s transfer obligations; the process and reversal risks depend on the payment system.
Settlement layer
The blockchain layer where Lightning channels are funded and settled, with transactions checked under Bitcoin’s rules.
SHA-256
Also called: SHA256.
A cryptographic hash function producing a 256-bit result, used in Bitcoin block and transaction calculations.
SHA-256d
Also called: SHA256d.
Applying SHA-256 twice, as used when hashing Bitcoin block headers.
Shamir secret sharing
Also called: Shamir, Shamir backup.
A method splitting a secret into shares so a chosen minimum can reconstruct it, while fewer reveal no secret.
side-channel analysis
Also called: side channel analysis.
Inferring secret information by observing effects such as a device’s power use or radio emissions, rather than reading the secret directly.
sidechain
Also called: sidechains.
A separate blockchain linked to Bitcoin through a transfer arrangement, with its own validation and trust assumptions.
signed transaction
A transaction with spending authorisations added; software must still check its other validity conditions.
Signing threshold
Also called: threshold.
The minimum number of required signatures in a multisig arrangement, such as two out of three keys.
Signing-key fingerprint
Also called: key fingerprint.
An identifier derived from a cryptographic signing key, used to compare and confirm which key is being trusted.
SIM swap
Also called: SIM swaps.
Taking control of someone’s mobile number through the provider, potentially intercepting calls or texts used for account recovery.
Single point of failure
One component or person whose loss or compromise can defeat an entire security or recovery arrangement.
SIPC
A US scheme addressing missing customer assets when a member brokerage fails; it does not insure investment market losses.
SLIP39
Also called: SLIP-39.
A standard encoding a wallet secret as recovery shares, including one-share and threshold backups; it differs from BIP39.
Snapshot
Also called: database snapshot.
A copy of data at one moment; a stale Lightning-state snapshot is not a safe live-channel restore.
SOCKS5
A protocol applications can use to send connections through a proxy, including a local Tor proxy.
soft fork
A rule change making some formerly valid blocks invalid without making formerly invalid blocks valid.
Software development kit
Also called: SDK.
Libraries and tools developers use to add a particular system’s features to an application.
Software fork
A separately developed version of an existing codebase; it need not create a different Bitcoin chain.
solo mining
Mining for a whole block reward rather than routine shared payouts; successful blocks may be extremely rare.
solo pool
A pool providing templates and submission services while each successful miner receives the block reward, minus the pool’s fee.
Source-available
Software whose source can be inspected, but whose licence may restrict use or redistribution more than open-source licences.
Spark
A Bitcoin payment system with operators and recovery rules different from standard Lightning channels; check its trust assumptions before relying on it.
Sparrow Wallet
Also called: Sparrow.
A desktop Bitcoin wallet supporting hardware signing, coin control and connections to servers or a full node.
Spending policy
Restrictions a signing device or service applies before approving a payment, which may include limits or waiting periods.
Splicing
Changing a channel’s funding with an on-chain transaction while keeping the channel, rather than closing and opening another.
spot bitcoin ETF
Also called: spot ETF, spot bitcoin ETFs.
An exchange-traded fund holding bitcoin to track its price, with custody and fund fees handled through intermediaries.
spread
Also called: bid-ask spread.
The difference between available buying and selling prices, which can add to a trade’s effective cost.
SPV
Also called: Simplified Payment Verification.
Checking transaction inclusion using headers and Merkle proofs, without independently validating every rule of every block.
SSD
Also called: solid-state drive.
Storage using electronic memory rather than spinning disks, suitable for frequent node database reads and writes.
SSH
Also called: Secure Shell.
A protocol for opening an encrypted remote command-line connection to another computer.
SSL
Also called: Secure Sockets Layer.
An older connection-encryption protocol; software interfaces sometimes still use this label for its modern successor, TLS.
stale block
Also called: orphaned block, stale.
A valid block outside the node’s selected most-work chain, often loosely called an orphaned block.
Static channel backup
Also called: SCB, channel.backup.
LND’s encrypted record of channel peers, used with the seed to request recovery closes rather than restore live channel state.
Static IP address
An IP address intended to remain the same, rather than change when a connection is renewed.
stock-to-flow ratio
Also called: stock-to-flow, S2F.
Existing supply divided by one year’s new production; it describes supply alone and does not predict demand or price.
store of value
Something held to preserve purchasing power for later; the term does not guarantee a stable price.
stranded energy
Energy available where there are too few buyers or transmission links to use it economically.
Stratum
Also called: Stratum protocol, Stratum V1.
A protocol through which mining hardware receives work from a pool and submits shares.
Stratum V2
A mining protocol including encrypted connections and miner transaction-selection negotiation, when the pool and software support those features.
Subkey
A key linked to an OpenPGP primary key, often assigned a specific task such as signing releases.
Submarine swap
An exchange between on-chain bitcoin and a Lightning payment linked by a shared secret and time limits.
Supply cap
Also called: 21 million cap, 21 million limit.
The upper limit on bitcoin issuance enforced by consensus rules; it depends on people continuing to enforce those rules.
Supply-chain attack
Also called: supply-chain tampering, supply chain tampering.
An attack compromising software, updates or distribution before the user installs or runs them.
Sweep
A transaction collecting spendable outputs into a wallet address, often after recovery or a channel close.
Sybil attack
One actor appearing as many participants, potentially making a privacy crowd or network look more independent than it is.
T
T+1
Trade settlement scheduled for the next business day after the trade date, rather than one calendar day later.
tail emission
A proposal to stop halvings at some point and pay a small fixed subsidy forever; it would change Bitcoin’s supply rules.
Taker
Also called: order taker, CoinJoin taker.
A participant accepting an existing trading offer or initiating a CoinJoin using makers’ available liquidity.
Taproot
A Bitcoin upgrade introducing version-one witness outputs and Schnorr signatures, with key-path and script-path spending options.
target
Also called: difficulty target.
The maximum hash value a Bitcoin block header may have under the current proof-of-work requirement.
taxable event
Also called: taxable events.
An action triggering a tax calculation or reporting duty, such as selling or spending bitcoin under some countries’ rules.
Terminal
Also called: command line.
A text interface for entering commands and reading a program’s responses.
TH/s
Also called: terahashes per second.
One trillion hash attempts per second: a speed measurement, not a quantity of bitcoin.
threat model
A plan identifying what you protect, possible attackers, how they could act and which defences fit your situation.
TIDES
OCEAN’s payout method, a PPLNS variant: miners earn only when the pool finds a block, split by their shares in a recent window.
Timelock refresh
Also called: refresh.
A confirmed self-payment resetting an output’s relative recovery delay by creating a new output.
timestamp
A recorded time value; a block timestamp is constrained by consensus rules but is not an exact measurement of mining completion.
Timestamp proof
Evidence that particular data existed by a certain time; it does not establish who created or approved it.
TLS
Also called: Transport Layer Security.
The protocol protecting modern encrypted connections, such as HTTPS, from eavesdropping and changes while data travels.
token protocol
Rules layered onto transaction data to represent separate tokens or records, additional to Bitcoin’s own spending rules.
Tor
A network routing connections through several relays to reduce the ability of one intermediary to link origin and destination.
Tor relay
A computer forwarding traffic within the Tor network as one part of a multi-relay route.
Toxic change
Leftover change from entering a CoinJoin; it isn’t mixed and stays linked to the original coin, so keep it apart from mixed coins.
Trampoline routing
Delegating route-finding to a Lightning node, trading convenience for additional information visible to that node.
transaction
Also called: Bitcoin transaction.
An instruction spending earlier outputs and creating new ones, subject to Bitcoin’s validity rules.
transaction fee
Also called: fee, mining fee.
Input value not assigned to transaction outputs, which the block’s miner may claim through the coinbase transaction.
Transaction index
Also called: txindex.
A node’s lookup index for finding historical transactions by their transaction identifiers.
Tx0
Also called: Whirlpool entry transaction.
A Whirlpool entry transaction splitting an input into pool-sized outputs, change and entry costs before mixing.
TXID
Also called: transaction ID.
An identifier calculated from a transaction’s non-witness serialised data; witness-only changes do not change a SegWit transaction’s TXID.
U
underclocking
Running hardware at a lower clock setting, usually reducing speed and power use; efficiency depends on the device and settings.
Uninterruptible power supply
Also called: UPS.
A battery-backed power supply that keeps equipment running briefly during an electrical outage.
unit bias
Preferring whole units over fractions even when the units represent the same economic amount.
unsigned transaction
A proposed transaction before the necessary spending authorisations have been added.
USB
A wired connection standard used for power and data; a USB-connected signing device is not physically air-gapped.
User experience
Also called: UX.
How a person experiences using an application, including its clarity, ease and behaviour.
user-activated soft fork
Also called: UASF.
A soft-fork activation approach in which node operators begin enforcing specified rules at a chosen time or height.
UTXO
Also called: unspent transaction output.
A transaction output not yet spent in the accepted chain; wallets add up relevant UTXOs to show a balance.
UTXO management
Organising and spending separate bitcoin outputs to manage transaction costs, change and public links between coins.
V
variance
How widely actual results can differ from their average, explaining why equal expected mining income can arrive unevenly.
virtual byte
Also called: virtual bytes, vB.
A size unit equal to four weight units; a transaction’s virtual size is its weight divided by four, rounded up.
volatility
How much and how quickly a price varies; it describes instability, not a guaranteed future direction.
voltage
Also called: volts.
Electrical potential difference, measured in volts; the miner and circuit must be designed for the supplied voltage.
voltage glitching
Manipulating a chip’s power supply to cause errors that may bypass protections or reveal secrets.
VPN
Also called: virtual private network.
An encrypted connection through a provider that can see your connection’s origin and destinations; it shifts rather than removes trust.
VSS server
Also called: VSS, Versioned Storage Service.
A storage service for versioned wallet state, supporting encrypted Lightning-state backups and recovery.
W
WabiSabi
A CoinJoin protocol allowing participants to contribute and receive different amounts while obscuring their input-output links.
wallet
Also called: Bitcoin wallet, software wallet.
Software or equipment managing payment keys and information; it can track a balance, prepare payments, or authorise spending.
wallet account
Also called: account.
A branch of a wallet’s key tree organising a separate group of receiving and change addresses.
wallet recovery
Also called: restore, wallet restore, recovery.
Rebuilding wallet access using the necessary backup information, compatible software and any additional secret the original setup used.
Wallet registration
Also called: registering a wallet.
Loading a wallet’s public configuration onto a signing device so it can check receiving addresses and change.
watch-only wallet
Also called: watch-only.
A wallet holding public information to track coins and prepare payments, without private keys needed to sign them.
Watching window
Also called: to_self_delay, CSV delay.
The agreed delay before a channel peer can spend their force-close output, allowing the other side to respond to cheating.
Watchtower
Also called: tower.
A service watching for revoked channel balances and publishing penalty transactions when it has the necessary information.
Watchtower client
The node component that sends encrypted breach-response information to a watchtower for channel states being revoked.
watt
Also called: watts, W.
A unit of power, measuring the rate of energy use; 1,000 watts equal one kilowatt.
weight unit
Also called: weight units, WU.
Bitcoin’s size measure: non-witness bytes count four weight units and witness bytes count one.
withdrawal fee
A service’s charge for releasing funds to your wallet; it may differ from the on-chain mining fee the service pays.
witness
The segregated part of a SegWit transaction carrying spending-authorisation data, including signatures.
Wrench attack
Also called: $5 wrench attack, physical coercion.
Physical threats or violence used to force a bitcoin holder to disclose secrets or transfer funds.
X
XOR
Also called: seed XOR.
A bit-combining operation used by some backup schemes, where all required parts must be combined to reconstruct the secret.
Z
zaps
Also called: zap.
Lightning tips associated with Nostr interactions, using compatible services and wallets.
ZH/s
Also called: zettahashes per second.
One sextillion hash attempts per second, equal to 1,000 EH/s.