Most commonly used in mathematics to refer to the four quarters of the coordinate plane.

Recall that the coordinate plane has an x-axis that divides into a top and bottom half, and a y-axis dividing into the left and right half. Together they create the four quadrants of the plane. Quadrantts of a coordinate plane By convention they are numbered one to four, the first quadrant being to the top right, and then going counter-clockwise from there

Also by convention they are often numbered using Roman numerals: I  II  III  IV.