Anti-aliasing and Anisotropic filtering explained
 

Multi sampling is a slightly more developed and intellectual approach to the problem. Multi sampling was introduced with DirectX 8. Rather than creating a larger, virtual image to calculate the samples, cards that multi-sample take the colour averages from the original image. Additionally, samples are reused for neighbouring pixels, meaning that less calculations have to be done.

As a 3D scene stretches into the distance, less detail is required as the objects become further away. Rendering textures that are far away at a lesser detail than those that are closer to the player means that graphics cards can give better performance. These lower-quality distance textures are called mipmaps.

Link
http://www.bit-tech.net/hardware/200...ltering/1.html