In the context of digital security, cryptography refers to the techniques and practices used to secure information by transforming it into an unreadable format, ensuring that only authorized parties can access the original data. It encompasses various methods like encryption, which converts plaintext into ciphertext, and decryption, which reverts the ciphertext back to readable format. Cryptography is vital for protecting sensitive data, ensuring integrity during transmission, and authenticating users in online transactions and communications.