ROT 13 (rotate by 13 places) is a simple letter substitution cipher that replaces each letter in the alphabet with a letter that is 13 positions ahead or behind it. The Caesar cypher, invented in ancient Rome, is used in this particular instance. ROT 13 is a symmetric encryption algorithm, meaning that applying it twice will give back the original text.
The way ROT 13 works is that it shifts each letter by 13 positions. The letter “A” becomes “N,” the letter “B” becomes “O,” the letter “C” becomes “P,” and so on in the case of Rotation 13 encoding. The alphabet wraps around, so ‘Z’ becomes ‘M’. Punctuation and digits are not encrypted and stay unchanged as they are not part of the alphabet.
Rotation 13 is often used as a simple form of encryption for messages that don’t require strong security. It is commonly seen in online forums or as a way to hide spoilers. Since the encryption is reversible by applying ROT 13 again, it is also used for simple text obfuscation or as a method to reverse the encryption.
For example, the phrase “Hello, World!” would be encoded as “Uryyb, Jbeyq!” using Rotation 13. To decode the message, you would apply Rotate 13 to the encoded text, which would give you back the original phrase.