Hexadecimal (or ‘hex’ for short) refers to the counting of numbers in base-16, in which there are 16 sequential digits in each unit. Since our standard decimal counting system only goes as far as 9 before we have to switch to another unit, hexadecimal is represented using the numbers 0-9 and the letters A-F. The following table provides a few examples of how decimal numbers ‘translate’ into hexadecimal.

Hexadecimal is often used by low-level programmers since it makes it easier to represent the binary numbers used at machine level (when debugging a program, or examining sectors on a disk using a sector editor, for example). A byte contains eight bits (binary digits), but the same eight bits can be represented using just two hexadecimal numbers.