The object of these games is to hit or throw the ball or bird over the net or against the wall back to the opponent.
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).
Some sports like Four square, Ballon au poing, Tamburello and Roundnet has the same logic of wall games using the floor or trampoline in the rebounding function.
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.