A file that is permanently stored by and on a blockchain, which contains relevant transaction data. A block is designed to record some or all of the most recent transactions not yet validated by the network. After data validation, the block is sealed.

A block is part of ordered records listed on a distributed database (the blockchain) where it is linked to other blocks using cryptography. The elements of a block are a cryptographic hash of the previous block, a timestamp, and transaction data.

The blockchain is a data structure that consists of a number of blocks linked to each other. Each block contains a number of transactions which represent the activity that’s recorded on the blockchain. Differently stated, a blockchain is a decentralized, distributed and public digital ledger where transactions across a network subject to a consensus building process. The records cannot be adjusted retroactively without adjusting all subsequent blocks and the consensus established across the respective blocks. Network nodes construct transactions into blocks, and if the transactions are successfully validated by the blockchain, blocks will be appended to the blockchain.

Validation (or mining) is the process of selecting transactions for inclusion into a block. It is performed by a node on the network known as a validator or miner. Nodes aggregate the transactions which are submitted to the blockchain. After validation, transactions are proposed to the next block on the blockchain. Selection of a block depends on the consensus mechanism adopted by the network. Most public networks use proof of stake (PoS), but certain others use proof of work (PoW), notably the Bitcoin network.

The attributes of each block include the block number, the block hash, the timestamp and the associated transaction count. Blocks are numbered sequentially from 0 in an upward, continuous series (the most up to date of which is called a block height). The block hash is a unique value of identification similar to a fingerprint that is generated cryptographically to identify a block. The block hash is constructed in hexadecimal format. The timestamp marks the moment at which the block was validated (and hence, mined) by the node that generated it.