Caesar's Cipher was named after Julius Caesar, who used this cipher to encrypt his private messages.
One of the simplest and most widely known ciphers is a Caesar cipher, also known as a shift cipher.
In a shift cipher the meanings of the letters are shifted by some set amount.
A common modern use is the ROT13 cipher, where the values of the letters are shifted by 13 places.
Thus 'A' ↔ 'N', 'B' ↔ 'O' and so on.