What is ROT13?
ROT13 (Rotate by 13) shifts each letter 13 positions forward in the alphabet. Since the alphabet has 26 letters, applying ROT13 twice returns the original text. A→N, B→O, C→P, etc.
History and Uses
ROT13 was widely used on Usenet newsgroups (1980s-90s) to hide spoilers, offensive jokes, and puzzle solutions — readers could decode by choice. It's still used for light obfuscation in puzzles, CTF competitions, and Reddit threads with spoiler content.
Is ROT13 secure encryption?
No. ROT13 provides no security — it's trivially broken and was never intended as encryption. Use it for spoiler hiding and puzzles only. For actual security, use proper encryption like AES.