Net sport
A net sport is a sport where a net is a standard part of the game, especially where the net separates the opponents. The object of these games is to hit the ball or bird over the net back to the opponent. Play typically begins with one side "serving" the ball/bird by initially tossing or releasing it and then hitting it over the net. This then starts a "rally", in which the sides alternate hitting the ball/bird over the net. Players then score points whenever the opponent fails to return the ball/bird back over the  net. The criteria on what is considered a valid return varies between each sport (such as the number of times the ball may be touched or bounced on a player's side before it must go back over the net). Net sports usually include: Although basketball, hockey, water polo, Football and other sports have netting around the goal area designed to more clearly indicate when goals are scored, they are not usually considered "net sports", since the net is not used to separate the teams involved, Similarly, lacrosse sticks have a loose netting that is used to catch and fling  the ball, but again lacrosse is not usually considered a "net sport". The Los Angeles Daily Times reports: "Net sports are unique in that the equipment is light, portable and affordable, and partners and opponents are easy to find. The sports are easy to learn, and the social aspect of the game[s] appeals to those who find the health club to be an isolationist palace of mirrors." The three "favorite" net sports (tennis, badminton, and volleyball) usually involve arching of the back when serving or spiking/smashing the ball or bird.