Grass courts are the fastest type of courts in common use. They consist of grass grown on very hard-packed soil, which adds additional variables: bounces depend on how healthy the grass is, how recently it has been mowed, 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 favour serve-and-volley tennis players.Grass courts were once among the most common tennis surfaces, but are now rare due to high maintenance costs as they must be watered and mown often, and take a longer time to dry after rain than hard courts. The grass surface, however, is the most physically forgiving to the human body because of its softness.Historically for the Grand Slams grass courts have been used at the Australian Open from 1905 to 1987, the US Open from 1881 to 1974, and Wimbledon since 1877.