Tennis is a sport usually played between two players (singles) or between two teams of two players each (doubles). Each player uses a racket that is strung with cord to strike a hollow rubber ball covered with felt over a net and into the opponent's court. The object of the game is to play the ball in such a way that the opponent is not able to play a good return. Tennis is an Olympic sport and is played at all levels of society at all ages. The sport can be played by anyone who can hold a racket, including people in wheelchairs.
The modern game of tennis originated in Birmingham, England, in the late 19th century as "lawn tennis". It had close connections both to various field ("lawn") games such as croquet and bowls as well as to the older raquet sport of real tennis. During most of the 19th-century in fact, the term "tennis" referred to real tennis, not lawn tennis: for example, in Disraeli's novel Sybil (1845), Lord Eugene De Vere announces that he will "go down to Hampton Court and play tennis.".
The rules of tennis have not changed much since the 1890s. Two exceptions are that from 1908 to 1961 the server had to keep one foot on the ground at all times, and the adoption of the tie-break in the 1970s. A recent addition to professional tennis has been the adoption of electronic review technology coupled with a point challenge system, which allows a player to contest the line call of a point.
Roger Federer (German pronunciation: [ˈfeːdərər]; born 8 August 1981) is a Swiss professional tennis player who, as of April 2013[update], is ranked world No. 2 by the ATP. Many sports analysts, tennis critics and former and current players consider Federer the greatest tennis player of all time. He owns several men's world records of the Open Era: holding the world no. 1 position for 302 weeks overall; a 237-consecutive-week stretch at the top from 2004 to 2008; winning 17 Grand Slam singles titles; reaching the finals of each Grand Slam tournament at least five times (an all-time record); and reaching the Wimbledon final eight times. He is one of seven men, and one of four in the Open Era, to capture the career Grand Slam, and one of three (with Andre Agassi and Rafael Nadal) to do so separately on clay, grass, and hard courts. Federer also shares the Open Era record for most Grand Slam titles at the Australian Open with Agassi and Novak Djokovic (4 titles), at Wimbledon with Pete Sampras (7 titles) and at the US Open with Jimmy Connors and Sampras (5 titles). Federer's ATP tournament records include winning six ATP World Tour Finals, playing in the finals at all nine ATP Masters 1000 tournaments (a record shared with Djokovic), and being one of three players (alongside Agassi and Djokovic) to win seven.