A tennis court is where the game of tennis

Tennis

Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...

 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.
Tennis is played on a rectangular flat surface, usually of grass

Grass court

A grass court is one of the four different types of tennis court. Grass courts are made of rye grass in different compositions depending on the tournament...

, clay

Clay court

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...

, concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 (hard court) or a synthetic suspended court. The court is 23.78 meters (78 feet) long, 10.97 meters (36 feet) wide. Its width is 8.23 meters (27 feet) for singles matches and 10.97 meters (36 feet) for doubles matches.