There are two types of clay courts: red clay and green clay. 

There are two types of red clay courts – the red American clay (deep burgundy red) consisting of red stone dust and brick dust and the red European clay (red / orange color) typically from Italian or Spanish crushed bricks. Roland Garros uses five layers of material (80 cm total or 31in) with a thin layer of terracotta brick dust on top. 

Clay courts are widely used in tennis courts, alongside hard courts, because they require less maintenance. Har-Tru’s green clay courts use metabasalt found in Virginia’s Blue Ridge Mountains, they are extremely hard,  angular natural greenstone. The particles assemble to form a stable playing surface. In fact, Har-Tru is installed throughout the United States on hard courts because it is more pleasurable for the body and reduces the number of common injuries caused by tennis court to the lower limbs. 

Clay courts are the slowest of all surfaces and generally produce a higher rebound compared to other options. Clay in many ways is an equalizer. The games are more strategic like a chess match. Players who rely on their service to earn more points, will usually have trouble getting up as the surface takes away many of the benefits of fast serve. Base players and players from all terrain will generally have better clay court performance. 

For most players, dirt surfaces are less worn at the joints of the ankle, knee and hip because they naturally absorb shocks and offer less traction. The reduction of traction allows the layers to slide on the court, which is the main reason why base players will generally play better on clay courts, while players that are less accustomed to the surface may have difficulty.