ROT-13 is a simple substitution cipher used to obfuscate Usenet posts. ROT-13 is not meant for use as a data encryption cipher.

ROT-13 is so named because every character is rotated 13 places.

ROT-13 “Encryption” Chart

Plaintext A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Ciphertext N O P Q R S T U V W X Y Z A B C D E F G H I J K L M

Encrypting ROT-13 ciphertext with ROT-13 again creates the original plaintext.