Rugby union, often simply referred to as rugby, is a full contact team sport which originated in England in the early 19th century. One of the two codes of rugby football, it is based on running with the ball in hand. It is played with an oval-shaped ball with a maximum width and length of 30 centimetres (12 in) and 62 centimetres (24 in) respectively, and is played on a field up to 100 metres (330 ft) long and 70 metres (230 ft) wide with H-shaped goal posts on each goal line. Historically an amateur sport, in 1995 the International Rugby Board (IRB) removed restrictions on payments to players, making the game openly professional at the highest level for the first time.

The IRB has been the governing body for rugby union since its formation in 1886. Rugby union spread from the Home Nations of Great Britain and Ireland, and was absorbed by many of the countries associated with the British Empire. Early exponents of the sport included Australia, New Zealand and South Africa. Countries that have adopted rugby union as their de facto national sport include Fiji, Georgia, New Zealand, Samoa, Tonga and Wales. Rugby union is played in over 100 countries across six continents and as of November 2010 118 unions were members of the IRB.

The Rugby World Cup, first held in 1987, takes place every four years, with the winner of the tournament receiving the Webb Ellis Cup. The Six Nations Championship in Europe and The Rugby Championship in the Southern Hemisphere (the latter replacing the Tri Nations) are major international competitions held annually. Major domestic competitions include the Top 14 in France, the English Premiership in England, the Currie Cup in South Africa, and the ITM Cup in New Zealand. Other transnational competitions include the Pro14, involving Irish, Italian, Scottish, South African and Welsh teams; The Rugby Championship, involving Argentina, Australia, New Zealand and South Africa; and the Heineken Cup, involving the top European teams from their respective domestic competitions.