Definition
Quadrant
One of the four regions formed when the x-axis and y-axis divide a plane.
What it means
The x-axis and y-axis split the coordinate plane into four regions. Start in the top-right region with Quadrant I, then count anticlockwise. The coordinate signs are I (+,+), II (−,+), III (−,−), and IV (+,−).
Remember it
Start top-right at I, then count anticlockwise around the grid.
Example
The point (−3, 4) is left of the y-axis and above the x-axis, so it lies in Quadrant II.
Watch for
A point such as (0, 5) lies on the y-axis, so it is not inside any quadrant.
Common mix-up
Quadrants are not numbered in reading order; the numbering moves anticlockwise from the top right.
Exact meaning
A quadrant is one of the four open regions made by the coordinate axes. They are numbered I, II, III, and IV anticlockwise from the region where both coordinates are positive; points on an axis are in no quadrant.