What is "z-order"

alt. 1 (context computer graphics English) The order in which objects should be drawn in order to display correctly. 2 (context computer graphics English) A property of a graphical object that indicates its position in the z-order. n. 1 (context computer graphics English) The order in which objects should be drawn in order to display correctly. 2 (context computer graphics English) A property of a graphical object that indicates its position in the z-order.

Z-order is an ordering of overlapping two-dimensional objects, such as windows in a graphical user interface (GUI), shapes in a vector graphics editor, or objects in a 3D application. One of the features of a typical GUI is that windows may overlap, so that one window hides part or all of another. When two windows overlap, their Z-order determines which one appears on top of the other.