ROT13

ROT13 is a very simple encryption mechanism for text. Imagine the 26 characters of the alphabet on a wheel. To ROT13 encrypt one character, simply rotate the wheel 13 positions from the original character position. To decrypt, turn the wheel another 13 positions. The purpose of ROT13 is not really encryption, but rather to shield the casual reader from potentially offensive material, or from what people call “spoilers” - i.e. giving away the end of a movie.