Z-axis
When referring to a three-dimensional plane, a z-axis refers to the depth of a three-dimensional object. In the picture to the right, the z-axis plane
goes front to back and intersects with the y-axis and z-axis. A good example of where the z-axis is used on a computer is in computer games or other 3-D environments, where you have a game character or other object moving
in a 3-D world.
