A coordinate plane is formed by the intersection of 2 axes. As there are only 2 axes in a 2-dimensional system, there's only one coordinate plane — the XY plane. But a 3-dimensional coordinate system has 3 coordinate planes — XY, ZX, and YZ planes, containing 2 axes each.^[1] However, it can be tricky to represent these 3 dimensions in the 2 dimensions of a screen or a piece of paper.