Hash Chain

A hash chain is a sequence of data blocks where each block contains the cryptographic hash of the previous block, creating a secure and linked history. This structure ensures that every block is cryptographically tied to the one before it, all the way back to the genesis block.

If any information in an early block is changed, the hash of that block changes, which invalidates the link to the next block, and so on. This makes it impossible to modify the past without recreating the entire chain, which is computationally expensive or economically impossible in a secure network.

The hash chain is the structural foundation of the blockchain's ability to provide a verifiable and immutable record of all transactions.