Cryptography is at the heart of blockchain technology, providing the security and trust needed for decentralized systems. Cryptographic techniques such as hashing and digital signatures ensure the integrity and authenticity of data. Hashing transforms data into a fixed-size string of characters, which is unique for every input, making it useful for verifying data integrity. Digital signatures allow users to sign transactions, proving their ownership and preventing unauthorized access. These cryptographic methods protect blockchain networks from fraud and malicious attacks.