What is a block?

Definition:

• A block is a data structure that holds a set of transactions or other relevant data. It is one of the building blocks of the blockchain.

Function:

• Contains Transactions: A block includes multiple transactions that have been bundled together.
• Links to Previous Block: Each block contains a reference (hash) to the previous block, creating a chain of blocks (hence “blockchain”).
• Ensures Data Integrity: Blocks use cryptographic hash functions to ensure that once data is written, it cannot be altered without changing all subsequent blocks.

Structure:

• Header: Contains metadata such as the block’s hash, the hash of the previous block, a timestamp, and sometimes information about the consensus process (e.g., a proof-of-work solution).
• Body: Contains the list of transactions or data entries.

Role in Blockchain:

• Blocks are added sequentially to the blockchain, each one building upon the previous one. This structure ensures that the blockchain is a continuous and immutable record of all transactions.