Cryptography is crucial for securing data and ensuring its integrity by transforming readable data into an unreadable format using encryption algorithms. This process protects information from unauthorized access and tampering, ensuring that only authorized parties can access and modify the data. Key cryptographic methods include encryption, which secures data both at rest and in transit, which generate unique hash values to verify data integrity; digital signatures, which authenticate the sender and confirm that the data has not been altered; and key management, which involves the secure generation, distribution, and storage of cryptographic keys. These techniques collectively safeguard sensitive information, maintain data integrity, and build trust in digital communications and transactions.