Tennis is a racquet sport which is either single that is it is played between two players or doubles which means it is being played between two teams of two players each. Each player hits the hollow rubber ball with a strung racquet. The ball is covered with felt which is at most times optic yellow in color however this is simply a tradition and not a rule and color of the ball being used to play tennis can vary from a range of color and a two tone ball is also acceptable. The idea is to strike the ball against the racquet in such a manner that it crosses over the net and lands on the other side that is the court of the opponent.