2D

2D is an abbreviation of "two dimensional" as in a 2D surface.

Game Maker produces 2D images on a screen that can represent 3D spaces and objects. Game Maker specifically produces programs using 2D graphics, but there is a limited set of 3D statements that can also be used in Game Maker. Specifically, these functions utilize Direct3D.

Coordinates
Coordinates in 2D are expressed in an x and y values.
 * X - The horizontal position of an object, not necessarily an object in Game Maker.
 * Y - The vertical position of an object, not necessarily an object in Game Maker.

In Game Maker draw functions, x and y values are used to specify where to draw something.