Simple definition of a Block
- Blocks are data structures within the blockchain database, where transaction data in a cryptocurrency blockchain are permanently recorded. A block records some or all of the most recent transactions not yet validated by the network.
- In case the foregoing is not clear:
- A valid block is a well-ordered set of transactions.
- Each block contains the hash of the previous block.
- Each block also includes a "winning lottery ticket", the nonce.
- The hash of the block has properties that are especially difficult to generate but very easy to verify.
- A well-ordered set of blocks that each contain well-ordered transactions is a well-ordered set of all transactions that have ever occurred.