Block
A batch of transactions bundled together, time-stamped, and cryptographically linked to the block before it.
Each block holds a list of transactions, a timestamp, and a reference to the previous block's hash. That backward link is what turns isolated blocks into a chain. Bitcoin adds a new block roughly every ten minutes; Ethereum, about every 12 seconds.
Blocks have size limits, so only so many transactions fit. When demand runs hot, users compete on fees to get in, and the rest wait in the mempool.
Related terms
A shared digital ledger that records transactions in linked batches, copied across many computers and hard to alter.
Block HeightThe number of blocks between a given block and the very first one, used to pinpoint its position.
TransactionA signed instruction that moves value or data on a blockchain, recorded permanently once miners or validators confirm it.
MempoolThe waiting room where broadcast transactions sit before a miner or validator picks them for a block.