What is a cipher?

[saolasosme]

Cipher is the algorithm that encrypts and decrypts messages, email, text, strings, etc.

Follow the numbers.
1.) The plaintext goes through 2.) a cipher or cipher block (suite), 3.) an encryption/decryption key is asked for, 4.) the result is the ciphertext, the encrypted data.

There are various types of ciphers DES (Data Encryption Standard) and AES (Advanced Encryption Standard) are common ones.

Ciphers algorithms that use one key for both encryption and decryption, are is a called Symmetric-key algorithms.