# Axis

**Axis** may refer to any of the following:

1. An **axis** is an imaginary line that passes through the origin point of a geometric coordinate system. Each dimension of the system has exactly one axis. For every point on an axis, the value of every other dimensional coordinate is zero. For example, in a two-dimensional space, every point on the X-axis has a Y-coordinate value of zero. In a 3-D space, every point on the X-axis has a Y-coordinate and Z-coordinate value of zero.

In the illustration shown here, there are three dimensions, and the axis for each is represented. The X-axis is oriented horizontally, the Y-axis is oriented vertically, and the Z-axis is oriented as approaching and receding from the point of view.

The interactive JavaScript below displays values which represent the distance of the mouse pointer, in pixels, from an origin point at the upper left of this document.

## Mouse position coordinates

2. A **chart axis** is the textual description of units displayed on each axis of a chart.

Absolute coordinates, Hardware terms, X-axis, Y-axis, Z-axis