Blockchain technology ensures data integrity through its decentralized and immutable ledger system, where each block contains a cryptographic hash of the previous block. This chaining of blocks makes it virtually impossible to alter any data without altering all subsequent blocks, thereby securing the entire chain against tampering. Additionally, consensus mechanisms, like proof of work or proof of stake, validate transactions and maintain the network's integrity. As a result, stakeholders have confidence in the authenticity and reliability of data recorded on the blockchain, making it essential for applications in finance and supply chains.