US Open (tennis)

The US Open is one of the four Grand Slam tennis tournaments. It is played in Queens, New York City in the USA. It is run by United States Tennis Association. The tournament has been played on three different surfaces:
The tournament was first played in 1881 for men, and 1887 for women. In 2006, the U.S. Open became the first Grand Slam to use Hawk-Eye. Hawk-Eye is a machine that can give a virtual replay of the shot that has just been played - this is useful for seeing if the ball was in or out. When a player does not agree with the umpire, they can ask to use Hawk-Eye. As of 2007, the other three Grand Slams use this machine too.
The US Open is the final Grand Slam of the year and is played over two weeks, in late August and early September.