A tennis court is where the game of tennis is played. It is a firm rectangular surface with a low net stretched across the center. The same surface can be used to play both doubles and singles.
A clay court is one of the four different types of tennis court. 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 tournaments.
Clay courts are more common in Continental Europe and Latin America than in the United States, Canada or Britain. In the United States, courts made of green clay, also known as "rubico", are often called "clay", but are not made of the same clay used in most European and Latin American countries. Although cheaper to construct than other types of tennis courts, the maintenance costs of clay are high as the surface must be rolled to preserve flatness. The water content must also be balanced; green courts are often sloped in order to allow water run-off.