Block is a structured unit of data added to a blockchain. Depending on the protocol, a block contains a set of transactions, metadata, and fields that allow nodes to verify its position and validity.

A block normally contains a block header and the block body. The exact structure varies between protocols.

Blocks in the chain

Blocks form an ordered sequence in which each block is linked to an earlier block. Its position is described by block height. The first block is called the genesis block.

After receiving a block, nodes validate its structure, transactions, and compliance with consensus rules. Competing blocks may temporarily exist, and the network can later resolve the competition according to protocol rules.