Blockchain technology ensures data integrity through its decentralized and immutable nature. Each block in a blockchain contains a unique hash of the previous block, creating a secure link that prevents unauthorized alterations. This chain of blocks is distributed across a network of nodes, where each node maintains a copy of the entire blockchain, promoting transparency and trust. Changes to any block are detectable because they would require consensus from the majority of nodes. Additionally, the use of cryptographic techniques further secures data against tampering, enhancing overall security.