Do you know tennis? If not, use this list as a refresher. Impress your tennis friends after your next match with one or more of these little-known facts.

• The net is 36" high in the center.


• 17-gauge string is more resilient than 15-gauge string, but will not last as long.


• In Australian doubles play, the server's partner stands on the same half of the court as the server.


• Canadian doubles is played with 3 people - one person against a doubles team.


• Grass is the fastest court surface, and produces the lowest bounce.


• The U.S. Open is the only Grand Slam event to be played on 3 different surfaces.


• A standard tennis ball weighs between 2 and 2-1/16 ounces.


• The tennis court is 78 feet long.


• The traditional scoring system in a tennis game is 15-30-40-deuce-ad-game is said to derive from the usage of the four quarters of a clock.


• On the NTRP rating system, 7.0 is a world class player.


• The Eastern forehand grip is the classic forehand grip, and sometimes called the shake hands grip.


• The Royal Tennis Court, built by Henry VIII in 1530, is the oldest tennis court in use in the world.


• The game of tennis originated in France before the 12th century.


• Lower string tensions generate more power.


• In doubles, when one partner calls a ball out and the other one good, the ball must be considered to have been good.


• Returning a service that is obviously out (accompanied by an out call) is a form of rudeness.


• The kick serve gives you the most time to get in to net for serve and volley play.


• If your opponent hits a winner and his/her foot touches the bottom of the net, it's your point.


• If your opponent's serve hits you before it bounces, it's your opponent's point.


• The serve is probably the most important shot in tennis but the least practiced.


• The mental side of the tennis is said to be 80 percent of the game.


• If you're not sure whether your opponent's shot is in or out, it's in.


• Rumor has it that if you beat Henry VIII in tennis, you stood a good chance of being beheaded.


• The game of tennis was originally played with the bare hand, later with a glove.


• The first Lawn Tennis Championships was instituted at Wimbledon in 1877, where the Gentleman's Singles was contested.


• The French Open was not held from 1940-1945 due to World War II.


• Slazenger has been the Official Supplier of Balls at Wimbledon since 1902.


• The women's singles was was first contested on the Center court at the French Open in 1928.


• Roland Garros, for whom the French Open venue was named, was a pioneer in aviation, but he was not a tennis player himself.


• Each of the Grand Slam tournaments have a different type of surface: Rebound Ace in Australia; clay at Roland Garros; lawn at Wimbledon and finally decoturf at Flushing Meadow The Australian Open was first played in 1905 at the Warehouseman's Cricket Ground in St Kilda Road, Melbourne.


• The Australian Open 2001 at Melbourne Park is the only Grand Slam venue with not only one, but two, retractable roofs.


• The first US National Championships for women were held in 1887, at the Philadelphia (PA) Cricket Club.


• The first U.S. National Championships were held in 1881 at the Casino in Newport, R.I., now home to the International Tennis Hall of Fame.


• The USTA National Tennis Center is the largest public tennis facility in then world with 33 outdoor courts and 9 indoor courts.


• You should restring your racquet throughout the year as frequently as you play tennis each week, and a minimum of once a year.


• A fresh tennis ball contains enough pressurized air so that it will bounce at least 53 inches when dropped from 100 inches above the ground onto a concrete slab.


• Regulation size tennis balls are 2 5/8 inches in diameter.


• The woven wool/nylon fur, called the nap, that covers the rubber ball must be either white or yellow in color.


• After about three hours of play, tennis balls begin to go dead.


• A player has scored a bagel when a set is won 6-0.


• The butt cap is a plastic piece on the tip of the racquet handle where there is usually a manufacturer's logo.


• A player willing to play out the long, difficult, and often slow matches that occur on clay courts is called a dirtballer.


• A baseline player who attempts to win points by keeping the rally alive until the opponent makes a mistake is called a pusher.


• The singles stick is 3 inches in diameter, and holds the doubles net at the appropriate height of 42 inches at each edge of the singles court.

Have fun on the courts!