For typical computer displays, "three-dimensional" is a misnomer—their displays are two-dimensional, for example, Metisse characterized itself as a "2.5-dimensional" UI. Semantically, however, most graphical user interfaces use three dimensions. With height and width, they offer a third dimension of layering or stacking screen elements over one another. This may be represented visually on screen through an illusionary transparent effect, which offers the advantage that information in background windows may still be read, if not interacted with. Or the environment may simply hide the background information, possibly making the distinction apparent by drawing a drop shadow effect over it.