Two classic stories in which deciphering a code plays an important role are The Gold Bug, by Edgar Allen Poe and The Adventure of the Dancing Men, by Arthur Conan Doyle.

Computer programs available on the Internet can analyze the letter frequencies in any text selection.

One of the most popular puzzles of Games Magazine is DSZQUPHSBNT! which involves breaking secret codes in which every letter is represented by another letter. Looking at letter frequencies is a productive way to begin to solve the puzzle.

The study of codes and ciphers is called cryptography.

The Navajo Indians’ native language was used as a code during World War II, and the code was never broken.

The Enigma Machine, a rotor based cipher machine, was a device for coding and decoding. Originally intended to be used for commercial cryptography, it was adopted by the German Army and Navy prior to World War II for sensitive communications.