Block

A block is a batch of transactions bundled together and added to a blockchain as a single unit. Each block carries a header with metadata—such as a timestamp, a reference (hash) to the previous block, and a summary of its transactions—plus the transaction data itself. Once accepted under the networks consensus rules, a block becomes a permanent part of the chain.

New blocks are produced at intervals that vary by network. A common misconception is that a block can hold unlimited data; in practice each block has size or capacity limits, so only a limited number of transactions fit into one.