The ROT13 Caesar cipher works by substituting each letter in a text using a fixed shift - for example, A becomes N, B becomes O, and so on. The number 13 was chosen because it's the offset from 'A' to 'N', a 13-letter rotation on the alphabet.
The ROT13 Caesar cipher is a simple substitution cipher that involves substituting one letter with the letter thirteen places in the alphabet. This type of cipher is popular among programmers in order to obfuscate certain parts of their code in order to prevent it from being stolen or tampered with. It has also been used in games and movies for when people are trying to hide clues.
This alphabetic rearrangement is also used as a means of censorship, such as with the popular website 4chan (www.4chan.org) where only those who know the password can read certain threads.
In summary, the ROT13 cipher is a simple and clever form of encryption in which the alphabet is rotated by 13 letters, in the same way that a person walks in a circle.