A cipher is a method of encrypting data to keep it secure from unauthorized access. It is an algorithm used to convert plain text into a secret code, making it difficult for anyone to read the message without the key to decode it. Ciphers can be used to protect confidential data, such as passwords, credit card numbers, and personal information.
There are different types of ciphers, including symmetric and asymmetric ciphers, which use the same or different keys for encryption and decryption.