Tennis is played on a number of different surfaces. Clay courts, hard courts, grass courts, and carpet courts are the four basic varieties of tennis courts, based on the materials used to create the surface. Grass courts were once typical tennis surfaces, but they are now uncommon due to expensive care expenses, as they must be watered and mowed often, require resting time between uses, and take longer to dry after rain than hard courts. Weather conditions have an impact on tennis courts; for example, people cannot use natural grass tennis courts in the winter since the grass is in poor condition and the ground is muddy. It is feasible to play only in the summer, or at certain seasons in the fall and spring.