Tennis is a racquet sport played between either two players or two teams of two players. Players use a stringed racquet to strike a hollow rubber ball covered in felt over a net into the opponent's court. In some places, tennis is still called lawn tennis, to distinguish it from real tennis, an older form of the game that is played indoors on a very different kind of a court. Originating in England in the late 19th Century, the game spread first throughout the English-speaking world, particularly among the upper classes.

Tennis is now an Olympic sport that is played at all levels of society and by all ages in many countries around the world. Its rules have remained remarkably unchanged since the 1920s. Along with its millions of players, millions of people follow tennis as a spectator sport, especially the four Grand Slam tournaments.