When video graphics cards became able to per-pixel addressing, graphics started to become very important to computers. The first graphics that a computer could do involved sprites. These sprites were limited to different character blocks that were installed in the extended ASCII code. This ASCII code changed between computers, and that is one of the reasons it was never permanently part of the ASCII code. How computers would make graphics out of this is by placing these characters in different parts of the scene, and by making them different colours. I'm sure that all of you Windows users are familiar with the blue scandisk scene which is show after a bad shut down. That makes use of ASCII characters to make a primative GUI.

Sprites

Sprites brought the use of graphics into the computer desktop. Sprites are basic 2D dimentional images, and by the use of layering, complex graphics can be made. All of the windows in a GUI based computer OS make use of sprite layers. When a window is minimized, the window's sprite layer is moved behind another layer, usually the desktop image. This makes it invisible, because it is no longer being drawn onscreen.

3D graphics are progressing at amazing rates. Through the use of dedicated video hardware acceleration, seemingly 3D worlds can be drawn onscreen in the form of games, 3D rendering, and 3D applications / 3D modeling. 3D graphics are much more complicated then 2D graphics, since they no longer rely on layered based sprites. Now each frame has to be drawn from scratch. The scene is saved as a series of vertexs to different polygons. Each of these polygons are usually mapped, or coated, in a texture. As you can see, 3D graphics are far more complex and computer intensive then 2D graphics. This is one of the major reasons why our OS desktop screens and GUI are still based in 2D graphics.