Wheelchair tennis is one of the forms of tennis adapted for wheelchair users. The size of courts, balls, and rackets are the same, but there are two major differences from pedestrian tennis: athletes use specially designed wheelchairs, and the ball may bounce up to two times, where the second bounce may also occur outside the court.
Wheelchair tennis is played at Grand Slams, and is one of the sports contested at the Summer Paralympics. There are three categories; Men, Women, and Quads; each category has singles and doubles tournaments. Quads is the category for quadriplegic players and it is sometimes called Mixed, especially at the Paralympic Games. Quads can use electric-powered wheelchairs, and players can hold rackets taped to the hand.
Wheelchair tennis increased in popularity in 1976 due to the efforts of Brad Parks, who is seen as the creator of competitive wheelchair tennis. In 1982, France became the first country in Europe to put a wheelchair tennis programme in place. Since then, much effort has made to promote the sport to rid it of the 'therapy' image that still affects many sports for disabled people.
The sport quickly became popular worldwide and was introduced to the Paralympic Games as a demonstration event at the Seoul 1988 Summer Paralympics. In 1990 wheelchair tennis was played alongside the abled players' event in Miami, this lasted for more than 15 years. It was at the 1992 Summer Paralympics in Barcelona that wheelchair tennis acquired the status of a full-fledged competition. The 2000 Summer Paralympics in Sydney boosted public appreciation immensely and led to the introduction of the sport to the four annual Grand Slams of Tennis. In 2004 the Quad category was added to the Paralympic Games.
The Wheelchair Tennis Class 8s at the 2002 Australian Open saw competitive wheelchair tennis take place at the same time and the same venue at a Grand Slam for the first time. In 2005 the Masters series was created, comprising all the events at the Grand Slams and the end of year championships, as Wimbledon and the US Open joined Melbourne. In 2007 Roland Garros joined and the Classic 8s were replaced by the Australian Open which had been held at the same venue two weeks later. In 2009 all events played at the abled players' Grand Slams were renamed Grand Slams.
The Netherlands has dominated numerous victories at major tournaments including the Paralympic Games and the Grand Slams.
Esther Vergeer holds the record for winning four Paralympic gold medals - one at the 2000, 2004, 2008 and 2012 Games. She holds the record for most consecutive women's wheelchair singles matches won.
For the 2013 season the ITF decided to adopt match tiebreakers in place of a third and deciding set in doubles matches. However the tiebreaker would only be used at events which were rated as ITF1 or lower and at the World Team Cup. The grand slams, however, were free to decide on the format of their tournaments.
The ITF Wheelchair Tennis Tour consists of international tournaments with different grades and prize money. The wheelchair tennis tournaments are graded by the ITF. Total prize money for the tour in 2016 was over $2million.  The wheelchair tennis tour includes the following types of tournaments:
The four Grand Slam -Australian Open, Wimbledon, Roland Garros, and US Open- include a wheelchair tennis draw. Only the US Open and Australian Open offer a quad draw so far, and only four Quad players are invited (as opposed to eight for men and women). In November 2017 it was announced that a Quad Wheelchair Doubles Exhibition match will be played in Wimbledon in 2018. 
The Super Series events include the Sydney Open (Sydney), Cajun Classic (Baton Rouge), British Open (Nottingham), Japan Open (Iizuka), US Open (St. Louis) and French Open (Paris, BNP Paribas Open de France). The ITF publishes a year-long calendar with all tournaments and their respective grades. 
The ITF BNP Paribas World Team Cup is a wheelchair tennis tournament for national teams, held annually since 1985. The BNP Paribas World Team Cup World Group event is played once a year, for men, women, quads and juniors. There are four continental qualification events in Europe, Africa, Asia and Americas, in which men and women compete to qualify for the main event. 
The last two major tournaments of the year are the Wheelchair Tennis Masters  (singles event) and Uniqlo Wheelchair Doubles Masters . The top eight men, top eight women and top six quads based on ranking are invited to compete there each year.
Wheelchair tennis is played at the Paralympic Games and FESPIC games as well.