A **coordinate plane **is a plane containing the *x*– and *y*-axes. The *x***-axis **is the horizontal line on a graph where *y* = 0. The *y***-axis **is the vertical line on a graph where *x *= 0.

The *x*-axis and *y*-axis intersect to create four **quadrants**. The first quadrant is in the upper right, and other quadrants are labeled counterclockwise using the roman numerals I, II, III, and IV. **Points**, or locations, on the graph are written as **ordered pairs**, (*x*, *y*), with the point (0, 0) called the **origin**. Points are plotted by counting over *x *places from the origin horizontally and *y* places from the origin vertically.