Blockchain

Block

Block is a data structure that contains a header and a set of transactions. Header is comprised of three items – the hash of the previous block’s header, metadata and a Merkle root. Metadata depends on the protocol. The Merkle root is a root of the well-known Merkle tree, which can be used to verify later that transactions in a block have not been tampered with.

Blockchain

A blockchain can be thought of as a series of blocks or an append-only data structure that resembles an ordered back-linked linked list, which uses hashes as pointers to previous blocks. This structure consists of blocks that form a chain, hence the term blockchain.