The base-16 numbering system that uses the digits 0 to 9, followed by the letters A to F (equivalent tot he decimal numbers 10 through 15). Hex is a very convenient way to represent the binary numbers computers use internally, because it fits neatly into the 8-bit byte. All of the 16 hex digits 0 to f can be represented in four bits, and so two hex digits (one digit for each set of four bits) can be stored in a single byte. This means that one byte can contain any one of 256 different hex numbers, from 0 through FF. Hex numbers are often labled with a lower-case h (for example,1234h) to distinguish them from decimal numbers.