Here is what I found from wiki.:
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Clay courts
Clay courts are made of crushed shale, stone or brick. The red clay is slower than the green, or Har-Tru "American" clay. The French Open uses clay courts, making it unique among the Grand Slam titles.
Clay courts slow down the ball and produce a high bounce when compared to grass courts or hard courts. For this reason, the clay court takes away some advantage of big serves, which makes it hard for serve based players to dominate on the surface.
Although more traditional and cheaper to construct than other types of tennis courts, the maintenance costs of a clay surface are higher than those of hard courts. Clay courts need to be rolled to preserve flatness. The clay's water content must be balanced; green courts generally require the courts to be sloped to allow water run-off.</div>
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Grass courts
Grass courts are the fastest type of tennis court in common use (AstroTurf is faster but is primarily only used for personal courts). They consist of grass grown on very hard-packed soil, similar to golf greens, which adds an additional variable: bounces depend on how healthy the grass is, how recently it has been mown, and the wear and tear of recent play. Points are usually very quick where fast, low bounces keep rallies short, and the serve plays a more important role than on other surfaces.
Grass courts tend to favor serve-and-volley tennis players, such as John McEnroe, Pete Sampras and as of late, the dominant grass courter Roger Federer. The International Tennis Hall of Fame in Newport, RI comprises grass courts. The surface is less firm and more slippery than hard courts, causing the ball to slide and bounce lower, and so players must reach the ball faster. Serve and volley players take advantage of the surface by serving the ball (usually a slice serve because of its effectiveness on grass) and then running to the net to cut off the return of serve, leaving their opponent with little time to reach the low-bouncing, fast-moving ball. Players often hit flatter shots to increase power and allow the ball to travel faster after and before the ball hits the ground. Grass courts were once among the most common tennis surfaces. However, due to high maintenance costs, grass courts are now rare as they must be watered and mowed often, and take a longer time to dry after rain than hard courts. For a more extensive discussion of the skills most advantageous on grass court, see grass-court specialist.</div>
