Most charts have an axis. The axis plays an important role in explaining the data to the user. A chart axis works like a scale for data plotted in a chart as well as a reference for what is being measured.

There are two primary types of chart axes. The first type is called a numeric axis, which is used to scale numeric data. The other primary axis type is called a category axis, this is used for categories such as time or dimensional values.

The use and design of the axis can have a profound impact on the way a user will interpret a chart.