Blockchain

A blockchain is a distributed ledger structure that groups validated records into cryptographically linked blocks maintained under a shared consensus process.

Each block typically references earlier data, making undetected alteration increasingly difficult as later blocks accumulate. Networks differ in who may participate, how consensus is reached, what information is public, and whether transactions can be changed through governance or protocol intervention. Blockchain does not make every input truthful or every application secure; smart-contract defects, key compromise, and off-chain dependencies remain possible.