The $x$ and $y$ axes divide the $xy$ plane in four right-angle domains which are called the quadrants of the plane. They are numbered going round the origin in anticlockwise direction so that $$\{(x,\,y) \mid x > 0, \,\,y > 0\}$$ is the first quadrant, $$\{(x,\,y) \mid x < 0, \,\,y > 0\}$$ the second quadrant, and so on.

Naturally, one can speak of the quadrants of the complex plane, too.