Blockchain data integrity refers to the accuracy and trustworthiness of information stored within a blockchain. Each block in the chain contains a set of transactions, and once data is added, it becomes very difficult to alter or delete. This is achieved through cryptographic hashing. Each block contains a unique hash that links it to the previous block.

If someone tries to change data in a block, its hash will change, breaking the chain. This makes it virtually impossible to manipulate past transactions without altering all subsequent blocks. Additionally, because blockchains are typically decentralized and maintained by a network of computers, any change needs consensus from the majority of the network.

This creates a robust security mechanism that protects the integrity of data. Ultimately, blockchain data integrity fosters trust among users, ensuring that transactions are secure, transparent, and verifiable. This reliability is one of the key features that sets blockchain apart from traditional databases.