Encrypt or decrypt text using the ROT13 cipher. ROT13 is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it.
ROT13 is a simple Caesar cipher with a shift of 13. It's commonly used in online forums to hide spoilers or potentially offensive content. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text, making it both an encryption and decryption method.