which is the x-axis
X-axis. When referring to the cartesian 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 as going left-to-right and intersecting both the y-axis and z-axis. A good example of what uses the x-axis is a computer mouse. As the mouse moves left or right the x-axis value increases and decreases, which allows the computer to know where the mouse cursor is on the screen. Below is a JavaScript script, which if enabled shows you the mouses x-axis and y-axis position as you move your mouse on your screen.