The Bitcoin Glossary
128 terms, defined in plain English.
DEEP DIVE →
At-the-Market Offering (ATM Offering)
A way for a public company to sell newly issued shares over time at prevailing market prices — a financing tool used by Bitcoin treasury companies.
92 cards link through to 89 dedicated deep-dive pages — highlighted below.#
A quarterly SEC disclosure revealing which institutions hold Strategy stock, spot bitcoin ETFs, and other U.S. equities — always a quarter out of date.
51% Attack
Controlling a majority of mining power to censor or reorder recent transactions — prohibitively expensive at current hashrate, and unable to steal keys or change the rules.
A
A string of letters and numbers — like an account number you can generate infinitely — where bitcoin can be received. Modern addresses start with bc1.
The total market value of client money a firm actively manages — not the same as a bank's balance sheet or a brokerage's client assets.
The bank that creates and redeems ETF shares in bulk — the plumbing that turns ETF flows into real bitcoin bought or sold on the spot market.
Air Gap
Signing transactions on a device that never connects to the internet (microSD, QR, NFC) — the Coldcard workflow.
Altcoin
Any cryptocurrency other than bitcoin. This site does not cover them, deliberately.
Application-specific integrated circuit — purpose-built mining hardware. See Miner (ASIC).
B
Batching
Combining many payments into one transaction to save fees — how exchanges process withdrawals.
Bear Market
A prolonged price decline. Bitcoin has had several exceeding 75% — and recovered from all of them so far.
BIP
Bitcoin Improvement Proposal — the public process for proposing protocol changes (BIP-39 seeds, BIP-85, etc).
A digital money and payment network with no company, government, or bank in charge — secured by cryptography and a fixed supply of 21 million coins.
The reference software: full node + wallet. See our full review.
A public company whose core business is holding bitcoin on its balance sheet — pioneered by Strategy (MSTR) in 2020.
Bitcoin's share of the total crypto market cap — around 56% in mid-2026. Rising dominance means money hiding in bitcoin; falling means risk appetite rotating to altcoins.
A trust an official can't see into or direct — the ethics device the CLARITY Act would require for federal officials' crypto holdings.
A batch of transactions bundled together, verified, and added to the blockchain roughly every ten minutes.
The running count of blocks since the genesis block — bitcoin's native clock, and how halvings are actually scheduled.
The new bitcoin a miner earns for adding a block — currently 3.125 BTC — plus all the fees from transactions inside it.
A public ledger of every Bitcoin transaction ever made, copied across thousands of computers and secured so that history cannot be rewritten.
Bull Market
A prolonged price rise. Historically has followed halvings — no guarantees.
C
Change
The “coins back” from a transaction — spending a 1 BTC UTXO to pay 0.3 returns ~0.7 to a change address you control.
Coin Control
Choosing exactly which UTXOs a transaction spends — a privacy and fee tool in wallets like Sparrow.
Coinbase Transaction
The special first transaction in a block that mints the reward — not the exchange of the same name.
The taxable profit between your cost basis and what you received when you disposed of bitcoin — realized only on sale, spend, or swap.
Holders selling at a loss under pressure — on-chain data can see it happening, and it has clustered near every major cycle low.
The stalled U.S. bill that would settle which digital assets are commodities vs securities — by statute, not by agency rule.
Keeping private keys on a device that never touches the internet — the standard for storing bitcoin savings.
Paying a third-party facility to run your mining machines on its power and cooling — you own the hardware, they own the power bill and the risk.
Confirmation
Each block mined after your transaction. Six confirmations (~1 hour) is the traditional finality standard for large amounts.
CPFP
Child-pays-for-parent: unsticking a low-fee transaction by spending its output with a high-fee child.
The Consumer Price Index — the Fed's main inflation gauge, and one of the biggest external forces on bitcoin's price through the rate path it informs.
Custodial
Any service that holds keys for you — exchanges, ETFs, most apps. Convenient, and someone else’s bitcoin until you withdraw.
D
What you paid to acquire a bitcoin lot, including fees — subtracted from sale price to calculate taxable gain or loss.
An options strategy — hold an asset, sell call options against it — used by bitcoin "income" ETFs like BTCI to generate yield in exchange for capping upside.
Digital Asset Treasury Company: an index-provider label for a firm holding over half its assets in crypto — the classification MSCI uses to decide if a bitcoin treasury company counts as operating or a fund.
Dollar-cost averaging: buying a fixed dollar amount on a fixed schedule, regardless of price — the strategy that removes timing (and emotion) from stacking.
A mechanism that releases bitcoin access to a designated heir if the owner stops checking in — core to inheritance planning without giving up keys today.
Bitcoin's self-tuning thermostat: every 2,016 blocks the network recalibrates how hard mining is.
Any event that ends your ownership of a bitcoin lot — selling, spending, or swapping — the trigger for a taxable gain or loss.
Saylor's term for Strategy's preferred-stock line — STRC, STRK, STRF, STRD — turning a bitcoin balance sheet into yield products.
The property that lets a digital asset behave like a physical one — impossible to copy or duplicate at will, enforced by proof of work.
Bitcoin’s self-tuning thermostat: every 2,016 blocks (~2 weeks) the network recalibrates how hard mining is, keeping blocks ~10 minutes apart no matter how much mining power joins or leaves.
Dust
UTXOs too small to be worth the fee to spend them — stranded sats.
E
A fund whose shares track bitcoin’s price inside a brokerage account. Exposure, not withdrawable coins — see our rankings.
The daily net money moving into or out of the spot bitcoin ETFs — creations minus redemptions, the cleanest public read on institutional demand.
A non-bank app offering bank products — accounts, cards, payments — with a chartered bank holding the deposits behind the scenes.
A valid block with no user transactions — only the coinbase paying the miner. Found in the one-to-two-second window before the full template arrives.
A business that trades fiat for bitcoin. Buy, then withdraw — see our rankings.
F
A 0–100 dial of crowd sentiment — volatility, momentum, and social chatter compressed into one number. 0 is panic, 100 is euphoria.
Fiat
Government-issued money backed by decree rather than a commodity — dollars, euros, yen.
The Federal Open Market Committee — the Fed body that sets US interest rates, eight times a year.
First-in, first-out — the default lot-accounting method assuming the oldest bitcoin you bought is the first you sold.
Fork
A change to the protocol rules. Soft forks tighten rules (backward-compatible); hard forks split the network.
Software that verifies every rule itself. See Node.
G
The 2025 federal law setting licensing and reserve rules for dollar-pegged stablecoins — the legal foundation behind Tether's USAT.
H
The scheduled event every 210,000 blocks (~4 years) that cuts the new-bitcoin issuance in half — the heartbeat of bitcoin’s fixed supply.
A small dedicated device that stores private keys offline and signs transactions internally — keys never touch your computer or phone.
A miner's expected daily revenue per unit of hashrate, in $/PH/s/day — the single number that summarizes mining profitability.
The total computing power securing the Bitcoin network, measured in hashes (guesses) per second — currently around a zettahash: 10²¹ guesses every second.
When a central bank holds rates steady but signals it's still leaning toward a future hike rather than a cut.
Bitcoin slang for holding through volatility instead of trading — born from a typo of "hold" in a 2013 forum post, now a philosophy.
A wallet whose private keys live on an internet-connected device — convenient like the cash in your pocket, and exposed like it too.
I
An accounting write-down recognizing an asset is worth less than its recorded value — how bitcoin's price swings hit corporate earnings without a single coin being sold.
Apple and Google's built-in payment system for digital goods sold in-app, carrying a commission of up to 30% — the rule Apple lifted for crypto payments in August 2026.
Inscription
Data embedded in transactions (Ordinals) — collectibles on bitcoin, and a fee-market wildcard.
K
KYC
Know Your Customer — the identity checks regulated exchanges must perform. Ties your identity to your addresses.
L
A North Korea-attributed hacking group behind some of the largest crypto thefts on record, including the 2025 Bybit breach.
Bitcoin’s payments layer: a network of payment channels on top of the blockchain enabling instant, near-free transactions — the difference between settling and spending.
Liquidity
How much can be traded without moving the price. Deep liquidity = tight spreads — why IBIT and Binance win their categories.
Coins unmoved for 155+ days — the market's strong hands. When this cohort sells at a loss in size, analysts call it capitulation; historically it clusters near bottoms.
Bitcoin whose private keys are gone for good — an estimated 2.3–3.7 million BTC, permanently out of the circulating supply. Most of it lost before 2013.
The strike price where expiring options are worth the least to holders — spot price often drifts toward it as an expiry approaches.
M
The waiting room for transactions: every broadcast payment sits in the mempool until a miner includes it in a block. Fuller mempool, higher fees.
The EU's harmonized rulebook for crypto-asset issuers and service providers, licensing exchanges and custodians across all 27 member states since December 2024.
A purpose-built computer that does exactly one thing — guess proof-of-work hashes — billions of times per second. ASIC: application-specific integrated circuit.
The competition that secures Bitcoin: specialized computers race to solve a cryptographic puzzle, and the winner adds the next block and earns new bitcoin.
Mining Pool
Miners combining hashrate and splitting rewards proportionally — steady income instead of lottery variance.
The share of an asset's value that comes from being used as money rather than from utility — gold's is most of its price; bitcoin's is all of it.
A wallet requiring multiple keys to spend — like a safe deposit box needing two of three keys. Removes the single point of failure that dooms most self-custody.
N
A cloud computing provider — often a former bitcoin miner — that leases GPU or data center capacity to AI labs instead of, or alongside, mining bitcoin.
A computer running Bitcoin software that independently verifies every block and transaction against the rules — your personal auditor of the money supply.
Nonce
The number miners iterate to change a block’s hash — the knob turned quintillions of times per second.
Not Your Keys
“Not your keys, not your coins” — custodial balances are IOUs until withdrawn. The lesson of every exchange collapse.
O
On-Chain
Settled on the blockchain itself, as opposed to Lightning or a custodian’s internal ledger.
Net Unrealized Profit/Loss — measures the market's aggregate paper profit or loss. A negative reading for long-term holders has coincided with past cycle bottoms.
A script opcode for embedding small amounts of provably unspendable data in a transaction — at the center of the 2026 blockchain-bloat debate.
The date a batch of options contracts settles, concentrating hedging flows into a single session.
P
A private key printed on paper — obsolete cold storage we recommend against. See why on our wallets page.
The stated $100 issue price a preferred share is designed to trade at — the reference point Strategy defends for STRC.
An extra word you memorize on top of the seed phrase (the “25th word”) — a second factor a thief cannot find on your backup plate.
Lock bitcoin once on-chain, pay instantly off-chain unlimited times — the building block of Lightning.
A legal document authorizing someone to act on your behalf if incapacitated — powerless for bitcoin without a paired technical access plan.
An exchange where event outcomes trade as $0–$1 shares, so prices read as crowd-sourced probabilities — Polymarket and Kalshi are the largest.
A share class paying set dividends, senior to common stock — how Strategy funds bitcoin buys (STRF, STRC, STRK, STRD).
Loans from funds, not banks — issued by project-level entities that keep debt off sponsors' books. The funding model behind AI data centers and miner expansions.
Cryptographic methods designed to stay secure against attacks from a sufficiently powerful quantum computer — bitcoin's current signatures don't qualify.
In the Softwar thesis, the idea that bitcoin's proof-of-work network projects real physical power into cyberspace to defend its ledger.
The secret number that controls bitcoin. Whoever knows it can spend the coins — full stop. Wallets exist to generate, guard, and use it without exposing it.
Proof of Reserves
An exchange cryptographically proving it holds client balances — Kraken, Binance, and OKX publish them; demand it from any custodian.
Bitcoin’s security engine: adding a block requires provably expending real energy, making history expensive to write and prohibitive to rewrite.
PSBT
Partially signed Bitcoin transaction — the file format that lets an offline device sign what an online computer prepared.
Public Key
Derived from the private key; proves signatures without revealing the secret. Addresses are derived from it.
R
RBF
Replace-by-fee: bumping a stuck transaction’s fee so miners pick it up.
The state law giving executors legal authority over digital assets like bitcoin — adopted, with real variation, in most U.S. states.
S
The smallest bitcoin unit (see Sats) — and the pseudonym of bitcoin’s creator, Satoshi Nakamoto, unheard from since 2011.
An asset investors buy during crisis because it holds value when everything else falls — gold, Treasuries, and (debatably) bitcoin.
Satoshis — the smallest unit of bitcoin. One bitcoin is 100 million sats, so a whole coin is optional; everyone stacks sats.
12 or 24 ordinary words that back up every key in your wallet. Anyone with the words has the bitcoin; anyone without them, including you, cannot recover it.
Holding your own private keys instead of trusting an exchange or custodian — the property that makes bitcoin different from every other financial asset.
SHA-256
The cryptographic hash function at bitcoin’s core — any input to a unique 256-bit fingerprint, one-way only.
Shamir Backup
Splitting a seed into N shares where any K recover it — supported by Trezor. No single piece of paper can lose or leak your wallet.
Coins acquired within the last 155 days — the market's fast money, quicker to buy on rallies and quicker to sell on fear.
A backwards-compatible tightening of Bitcoin's rules — old nodes keep following the chain. How P2SH, SegWit, and Taproot all shipped.
A national government's treasury holdings of bitcoin — distinct from whether bitcoin is accepted as legal tender.
Price zones where buyers or sellers repeatedly act. A level flips role once price closes through it and defends the retest.
Stacking Sats
Accumulating bitcoin steadily in small amounts — DCA culture’s term of art.
T
Taproot
The 2021 upgrade improving privacy and script flexibility — bc1p addresses.
Timelock
A condition making coins unspendable until a set time or block — the mechanism behind inheritance schemes and Green’s 2FA recovery.
Transaction Fee
What you pay miners for block space, priced in sats/vB — set by demand (see Mempool), not by amount sent. $10 or $10M can cost the same to move.
U
Unspent transaction output — the actual form bitcoin takes on-chain. Your balance is not a number; it is a collection of discrete coins of various sizes.
V
Volatility
The size of price swings. Bitcoin’s is famous — the cost of admission for its returns, and the reason position sizing matters.
W
Software or hardware that manages your keys and talks to the network. Wallets hold keys, not coins — the bitcoin lives on the blockchain.
The price the weekly candle opened at — 00:00 UTC Monday. A shared reference for weekly bias, not a mechanical barrier.
An entity holding enough bitcoin to move markets — commonly 1,000+ BTC, tracked on-chain in real time.
Watch-Only
A wallet that sees balances but holds no keys — monitor cold storage from your phone safely (BlueWallet, Sparrow).
Whitepaper
“Bitcoin: A Peer-to-Peer Electronic Cash System” — Satoshi’s nine pages from October 2008 that started it all.