# 1. Introduction

You should have already covered the idea of base systems, and looked at how to work with both denary and binary. If you haven't, **CLICK HERE**.

In this section, we will discuss a third base system that is commonly used in computer science: Hexadecimal (commonly abbreviated as "Hex").

Denary numbers are "base-10" because they use ten symbols, and binary is "base-2" because it uses two symbols. So hexadecimal, which uses sixteen symbols, is "base-16".

### Why use hexadecimal?

Hexadecimal is useful because it is much more readable to humans than binary, but at the same time it still shares a lot of the qualities of binary. It is widely used in computing because it is a much shorter way of representing a "byte" of data (8 binary digits or bits).

If we were to represent a byte of data in binary, it would require 8 digits, e.g. "10100110".

However, that same byte of data could be represented in hexadecimal in just two digits e.g. "A6". This is much more compact and user friendly than a binary number.

Since a byte is 8 digits long, it has a maximum value. In denary, this is 255. The same number can be written as 11111111 in binary, or FF in hex.