Fake Grass is a man-made surface manufactured from synthetic made to look like natural grass. It is most often used in arenas for sports that were originally or are normally played on grass. However, it is now being used on residential lawns and commercial applications as well. The main reason is maintenance — fake grass resists heavy use (such as sports) better, and requires no irrigation or trimming.
Artificial turf is commonly known as Astroturf, an example of a genericized trademark.