Turn the TV on to one of the cable sports channels anytime and there's a pretty good chance you'll see two or four powerfully built young people grunting and yelling as they smash a rubber ball across a net. Such is the modern style of tennis, once the genteel afternoon pastime of the idle rich. Lawn tennis, to give the sport its full title, developed from real tennis, an indoor game that dates back to twelfth or thirteenth-century France, when balls were hit with the palm of the hand. Rackets weren't developed until the sixteenth century, when the game became popular among aristocrats and was played in a walled court.