Encryption is covered in full, together with the reverse process, in the entry Data Encryption and Decryption, which explains the main methods, key management and their role in banking, payments and crypto. This page gives a short definition and explains why the topics share an entry.
Encryption is the process of converting readable information, called plaintext, into scrambled ciphertext using a mathematical algorithm, or cipher, and a secret key. Without the right key, the ciphertext cannot practically be turned back into the original. Symmetric encryption, such as the Advanced Encryption Standard, uses one shared key and is fast enough to protect large volumes of stored data and card transactions. Asymmetric encryption uses a public key to lock data and a private key to unlock it, and underpins secure web connections. Banks and payment firms encrypt data in transit and at rest to meet security standards and privacy laws, and messaging apps use end-to-end encryption so that even the service provider cannot read messages. Public blockchains, by contrast, rely mainly on hashing and digital signatures rather than encryption, since their records are meant to be readable by everyone.
Encryption and decryption are two halves of one process, so this site covers them together, with the wider science described under cryptography.