Bitcoin Glossary

B

Block

A batch of transactions, cryptographically chained to the one before it, added to the ledger roughly every ten minutes.

Also called: blocks, block height

C

Cold storage

Keeping the keys that control bitcoin on a device that has never been connected to the internet.

Also called: cold wallet, offline storage

Confirmation

A count of how many blocks have been mined on top of the block containing a transaction.

Also called: confirmations

Custody

The arrangement by which someone holds the keys to bitcoin on another party's behalf.

Also called: custodian, qualified custodian

D

Difficulty adjustment

The automatic recalibration, every 2,016 blocks, that keeps blocks arriving roughly ten minutes apart.

Also called: difficulty retarget

F

Fee rate

What a transaction pays for block space, quoted per unit of size rather than as a percentage of the amount sent.

Also called: transaction fee, sats per vbyte

Full node

Software that independently verifies every rule of the Bitcoin protocol rather than trusting anyone else's word.

Also called: node, bitcoin node

H

Halving

The scheduled event, every 210,000 blocks, at which the reward for mining a block is cut in half.

Also called: halvening, block subsidy halving

Hashrate

The total computational power miners are pointing at the Bitcoin network, measured in hashes per second.

Also called: hash rate, network hashrate

L

Lightning Network

A payment layer built on Bitcoin that settles most transfers off-chain, keeping them fast and cheap.

Also called: Lightning, LN

M

Mempool

The waiting room of transactions that have been broadcast but not yet included in a block.

Also called: memory pool

R

Recovery phrase

The list of words from which every key in a wallet can be regenerated. Anyone who reads it can spend the funds.

Also called: seed phrase, mnemonic, backup phrase

U

UTXO

An unspent transaction output: a discrete chunk of bitcoin that a future transaction can consume.

Also called: unspent transaction output, UTXOs

B