A block header is used to identify a particular block on an entire blockchain and is hashed repeatedly to create proof of work for mining rewards. A blockchain consists of a series of various blocks that are used to store information related to transactions that occur on a blockchain network. Constituents of Block Header are: Timestamp (4 bytes), Version Number (4 bytes), Merkle Root (32 bytes), Difficulty Target (4 bytes), Nonce (4 bytes), Previous Block Hash (32 bytes).