Table tennis, also known as ping-pong and whiff-whaff, is a sport in which two or four players hit a lightweight ball, also known as the ping-pong ball, back and forth across a table using small rackets. The game takes place on a hard table divided by a net. Except for the initial serve, the rules are generally as follows: players must allow a ball played toward them to bounce one time on their side of the table, and must return it so that it bounces on the opposite side at least once. A point is scored when a player fails to return the ball within the rules. Play is fast and demands quick reactions. Spinning the ball alters its trajectory and limits an opponent's options, giving the hitter a great advantage.The game was invented in England in the early days of the 20th century and was originally called Ping-Pong, a trade name. The name table tennis was adopted in 1921–22 when the old Ping-Pong Association formed in 1902 was revived. The original association had broken up about 1905, though apparently the game continued to be played in parts of England outside London and by the 1920s was being played in many countries.