* Codes, ciphers, and codebreaking have been around for millennia, with the survival of nations sometimes hanging on the security of codes and ciphers. With modern computer networking, they have become important in day-to-day life. This document provides a technical and historical introduction to codes, ciphers, and codebreaking. It is also available in a downloadable archive, formatted in HTML, for reading on a tablet or other viewer.
Those who prefer a less detailed treatment of the subject may be interested in the brief A Codes & Ciphers Primer document.