Definition:Cartesian Plane/Quadrants

Definition
For ease of reference, the cartesian coordinate plane is often divided into four regions by the axes:
 * $(1): \quad$ The area above the $x$-axis and to the right of the $y$-axis is called the first quadrant.
 * $(2): \quad$ The area above the $x$-axis and to the left of the $y$-axis is called the second quadrant.
 * $(3): \quad$ The area below the $x$-axis and to the left of the $y$-axis is called the third quadrant.
 * $(4): \quad$ The area below the $x$-axis and to the right of the $y$-axis is called the fourth quadrant.

Note that the axes themselves are generally not considered to belong to any quadrant.