X-axisWhen referring to a two and three-dimensional plane, the x-axis or horizontal axis refers to the horizontal width of a two or three-dimensional object. The illustration shows the x-axis plane going left-to-right and intersecting with the y-axis and z-axis. A good example of where the x-axis is used on a computer is with the mouse. By assigning a value to the x-axis, when the mouse is moved left-to-right the x-axis value increases and decreases, which allows the computer to know where the mouse cursor is on the screen.

Also see: Axis, Y-axis, Z-axis