Tennis is a sport played by millions of people. Tennis was played as far back as the Middle Ages in France or way back in Ancient Greece. King Henry VIII played tennis and he was pretty good but modern tennis wasn't played until 1873 in England. There was tennis in the Olympics from 1896 until 1924. It returned in 1984 as a demonstration sport and became an official Olympic sport in 1988. There are also professional tournaments like the US Open, the French Open, and the Australian Open, but the best known of all the professional tennis tournaments takes place in Wimbledon, England.To play tennis you need a ball, a racket, a net, and of course, people. In the olden days, the strings of a tennis racket were made of sheep, cow, or ox intestines. Today the strings are made of artificial threads. A tennis ball is hollow and a little smaller than a baseball. It is made of 2 elastic halves joined together and covered by a layer of wool and synthetic threads that make it feel fuzzy. The object of the game is to hit the ball on the ground of the opponent's side of the court without them hitting it back to your side. A singles match is a game of tennis played by two people, one on each side of the net. It takes four people, with two on each team, to play a doubles match. It is played on a rectangular court of grass, concrete, or clay. The court for singles is a rectangle 78 feet long x 27 feet wide and for doubles the court is 78 feet long x 36 feet wide. Players score by winning points, sets, and matches. You get a point by hitting the ball in the ground on the opponent's side without them hitting it back on yours. You can also get a point if the ball hits the other player's body, bounces twice before the other player can get to it, if the other player hits the ball outside the court, or can't get it over the net. If a second serve is bad, the player loses a point. Each game has four point, they are called 15, 30, 40 and then game. The player has to win six games to win a set. Men have to win three out of five sets and women have to win two out of three sets. At the Olympics there will be men's singles, women's singles, men's doubles, and women's doubles.