The game of tennis most commonly played today has been adapted from a much earlier game called Court Tennis, Real Tennis, or Royal Tennis (depending on where you live).
Modern tennis is played on a special court divided by a net, with a single player at each end (singles), or a team of two players at each end (doubles). Players use racquets to hit a ball back and forth, either on the full or after a single bounce. There are many sites listed in this category which can give you a better understanding of how the game is played.
Not many sites should be listed directly in this category. There is usually a more appropriate subcategory or related category.
Sites in languages other than English belong in the World/ hierarchy.
Sites selling tennis gear online belong in the Shopping hierarchy.
Sites relating to a specific area and primarily of interest to people residing in that area (such as local tennis clubs belong in the Regional hierarchy.
Sites about the manufacture of tennis equipment and courts usually belong in the Business - Sporting Goods or Construction - Athletic and Recreational Surfaces hierarchy.