Bitcoin Glossary

This glossary covers key Bitcoin network, mining, pool, and operational terms in plain English.
Use your browser search (Ctrl+F / Cmd+F) to find a term fast.

A

• 51% Attack — When an attacker controls the majority of network hashpower (PoW) and can attempt reorgs/double-spends.
• ASIC — Application-Specific Integrated Circuit; dedicated hardware optimized for SHA-256 mining.
• ASICBoost — A set of techniques that can improve ASIC efficiency by reusing work in hashing (implementation-dependent).
• AuxPoW — Auxiliary Proof of Work; allows merged mining so one PoW can secure multiple chains (e.g., some AuxPoW networks).

B

• Block — A set of confirmed transactions appended to the blockchain.
• Block Height — The number of blocks from genesis to the current block (an index of chain progress).
• Block Header — Metadata miners hash (prev block hash, merkle root, timestamp, nBits/target, nonce, etc.).
• Block Reward — Total miner payout per block: block subsidy + transaction fees.
• Block Subsidy — Newly issued BTC paid to miners in each block (cuts at each halving).
• Block Template — Candidate block data used for mining; pools build templates and distribute work to miners.
• Block Time — Average time between blocks (Bitcoin targets ~10 minutes).

C

• CB (Coinbase) — Shorthand for the coinbase transaction or coinbase field; context-dependent.
• Chain — The ordered history of blocks recognized by nodes (the “best chain” has the most accumulated work).
• Confirmations — Number of blocks mined on top of a transaction’s block; higher confirmations reduce reorg risk.
• Coinbase Transaction — The first transaction in a block that creates the miner’s reward output(s).
• CPFP (Child Pays For Parent) — Fee strategy where a high-fee child transaction helps confirm a low-fee parent.

D

• Difficulty — How hard it is to find a valid block; rises when hashrate rises over time.
• Difficulty Adjustment — Bitcoin recalibrates difficulty every 2016 blocks to keep ~10-minute block times.
• DNS — Domain Name System; misconfigured DNS can increase latency or cause pool connection instability.
• DDoS — Distributed Denial of Service; flooding traffic to disrupt services (pools mitigate this heavily).
• Double Spend — Attempting to spend the same coins twice, usually requiring timing and/or reorg capability.

E

• EH/s — Exahashes per second; 10¹⁸ hashes per second.
• Eclipse Attack — Isolating a node by controlling its peer connections, influencing what it sees as the network state.
• ExtraNonce — Additional nonce space used by miners/pools (often in coinbase) to expand the search space.

F

• Failover — Automatic switching to backup pool endpoints if the primary endpoint fails.
• Fee Rate — Transaction fee density, commonly quoted as sat/vB (satoshis per virtual byte).
• Fees (Transaction Fees) — Fees paid by users; miners collect them in blocks.
• Firmware — Miner software controlling hashing behavior, clocks/voltage, fans, networking, and stability.
• FPPS — Full Pay Per Share; pays an expected value per share for both subsidy and fees.
• FPPS+ — Not a universal standard; “+” varies by pool’s payout policy and may include extras or different fee handling.

G

• Genesis Block — The first block of the Bitcoin blockchain (block 0).
• GH/s — Gigahashes per second; 10⁹ hashes per second.

H

• Halving — Event that reduces block subsidy roughly every 210,000 blocks.
• Hash — Output of a hashing function; miners compute hashes repeatedly to find values under a target.
• Hashboard — ASIC miner board containing hashing chips; multiple hashboards form a miner’s total hashrate.
• Hashrate — Rate of hashing work (for a miner, pool, or the network).
• Hashprice — Expected revenue per unit of hashrate (e.g., $/TH/day or $/PH/day), before power/opex.
• Heat Dissipation — The ability to remove heat from miners; critical for stability and lifespan.

I

• Immersion Cooling — Cooling miners by submerging them in dielectric fluid to improve thermals and reduce noise.
• Invalid Share — A submitted share that fails validation (often instability, wrong settings, or hardware errors).

J

• J/TH — Joules per terahash; the key efficiency metric for SHA-256 ASIC miners.
• Job (Stratum Job) — Work assignment sent by pool to miner (template + target + parameters).

K

• kH/s — Kilohashes per second; 10³ hashes per second (rarely used in modern SHA-256 mining contexts).

L

• Latency — Network delay (RTT); high latency usually increases stale shares.
• Lightning Network — A Layer-2 payment network enabling fast, low-cost BTC transactions off-chain.
• Luck (Pool Luck) — Deviation between expected vs actual block finds over time due to randomness (variance).

M

• mH/s — Megahashes per second; 10⁶ hashes per second (legacy scale for older hardware eras).
• Mempool — Unconfirmed transactions waiting to be mined into blocks.
• Merkle Root — A single hash representing all transactions in a block via a Merkle tree.
• Merkle Tree — Hash tree structure used to efficiently prove transaction inclusion in a block.
• Miner — Hardware and/or operator performing hashing to secure the chain and earn rewards.
• Mining Pool — A service that aggregates miners’ hashrate and shares rewards based on contributed work.
• Merged Mining — Mining multiple chains simultaneously using the same proof-of-work, when supported.

N

• nBits — Encoded target difficulty field in the block header (compact representation of target).
• Network Hashrate — Estimated total hashrate securing the network (inferred from blocks + difficulty).
• Nonce — Value miners vary in the block header to search for a valid block hash.

O

• Orphan Block — A valid block that does not end up in the main chain due to competing blocks (reorg outcome).
• Overclock — Running hardware above default frequency for higher hashrate (often increases power/heat and risk).

P

• Packet Loss — Dropped network packets; increases rejects/stales and lowers effective hashrate.
• Payout Threshold — Minimum balance needed before a pool sends a payout.
• Payout Schedule — How often payouts are processed (e.g., hourly/daily/when threshold met).
• PDU — Power Distribution Unit; distributes electrical power to multiple miners in a rack/farm.
• PH/s — Petahashes per second; 10¹⁵ hashes per second.
• PPLNS — Pay Per Last N Shares; rewards based on shares within a rolling window (higher variance).
• PPS — Pay Per Share; stable expected value paid per share (pool absorbs variance for covered reward component).
• PPS+ — Hybrid: subsidy paid PPS-style while transaction fees are distributed based on actual blocks (often windowed).
• Pool Fee — Percentage retained by the pool for operations and service (varies by payout method and policy).
• Propagation — How quickly blocks/transactions spread across the network; affects stale/orphan risk.
• Proxy (Mining Proxy) — Relay that aggregates miner connections and forwards them to the pool (common in farms).
• PSU — Power Supply Unit; converts AC to stable DC power for miners.

Q

• Queue (Job Queue) — Buffered work/jobs; too much buffering can contribute to stales if new templates aren’t applied fast.

R

• RBF (Replace-By-Fee) — Fee mechanism allowing a transaction to be replaced with a higher-fee version (if signaled).
• Rejected Share — Share not counted by the pool (commonly stale, invalid, duplicate, or low difficulty).
• Reject Rate — Percentage of shares rejected; a key KPI for miner-to-pool performance.
• Reorg (Chain Reorganization) — When the best chain tip changes and some recent blocks are replaced.
• Round — In pool contexts, a period between found blocks (used in some payout accounting models).
• RTT — Round-trip time; basic latency metric (ping-like measurement).

S

• sat/vB — Satoshis per virtual byte; standard fee rate unit in Bitcoin.
• Selfish Mining — Strategy where a miner/pool withholds blocks to gain advantage (theoretical and practical considerations vary).
• Share — Proof-of-work submission meeting pool share difficulty; used to measure contributed work.
• Share Difficulty — Pool-defined difficulty required for shares; often adjusted (VarDiff).
• Share Rate — How frequently a miner submits shares; influenced by hashrate and share difficulty.
• Slush Score / Score-Based — Payout methods that weight shares by time to reduce pool-hopping advantages (implementation varies).
• Solo Mining — Mining without a pool; rewards are rare but full reward goes to the miner when found.
• SPV (Simplified Payment Verification) — Lightweight verification method that doesn’t download the full blockchain (uses headers/merkle proofs).
• Stale Share — A valid share submitted after the pool has moved to new work (new template), so it’s not credited.
• Stale Rate — Percentage of stale shares; strongly affected by latency and job switching behavior.
• Stratum — Mining protocol used to distribute jobs and accept share submissions.
• Stratum URL — Pool endpoint miners connect to (e.g., stratum+tcp://host:port or stratum+ssl://host:port).
• Stratum V2 — Newer mining protocol family aimed at better security and efficiency; adoption depends on pool/firmware.

T

• Target — Threshold a hash must be below to be valid (block target vs share target).
• Template Switch — When a miner changes work due to a new block or updated mempool/fees; slow switching increases stales.
• Thermal Throttling — Automatic slowdown when temperatures exceed safe limits, reducing hashrate.
• TH/s — Terahashes per second; 10¹² hashes per second.
• Timestamp — Block header time field; miners can adjust within protocol limits.
• Tx (Transaction) — A transfer of BTC expressed as inputs (UTXOs) and outputs.
• TXID — Transaction identifier (hash of the transaction data).

U

• Underclock — Running hardware below default frequency to reduce power/heat (often improves stability).
• Uptime — Percent of time a miner stays connected and hashing without interruption.
• UTXO — Unspent Transaction Output; the “coin” model Bitcoin uses for balances and spending.

V

• Valid Share — Share accepted by the pool and credited for payout calculations.
• VarDiff — Variable difficulty; pool adjusts share difficulty to keep share submission rate stable.
• vB (Virtual Byte) — Transaction size unit used for fee calculation in SegWit-era Bitcoin.

W

• Wallet Address — Destination address used for payouts.
• Worker — Named miner identity under an account used to monitor hashrate and performance.

Z

• ZH/s — Zettahashes per second; 10²¹ hashes per second (network-scale metric).

Disclaimer: This content is for informational purposes only and does not constitute financial or investment advice.