Codes And Secret MessagesHere you will find The Problem Site's oldest "Reference" pages; these pages were written to help explain a few different kinds of codes to students. The codes range from complex matrix codes to simple letter substitution codes. Click the links below to find out about each kind of code.
A simple code created by reversing the letters of the alphabet and substituting.
Another simple code which shifts the alphabet instead of reversing it.
One of the most popular pages on this site, this page explains the sort of code computers use.
Hexadecimal is really just base 16, but it is commonly used when dealing with computers, since it is closely related to base two.
A more complex mathematical code involving matrices.
This code was designed not for secrecy, but to transmit information in the early days of long distance communication.
A way of writing text in which symbols and numbers are substituted for letters which are similar in appearance