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 length and width of 30 centimetres (12 in) and 62 centimetres (24 in) respectively. It 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.

William Webb Ellis is often credited with the invention of running with the ball in hand in 1823 at Rugby School when he allegedly caught the ball while playing football and ran towards the opposition goal. However, the evidence for the story is doubtful. In 1845, the first football laws were written by Rugby School pupils; other significant events in the early development of rugby include the Blackheath Club's decision to leave the Football Association in 1863 and the split between rugby union and rugby league in 1895. 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.

Sonny William 'Sonny Bill' Williams (born 3 August 1985) is a New Zealand rugby union player, heavyweight boxer and former rugby league player. He is only the second person to represent New Zealand in rugby union after first playing for the country in rugby league. In rugby union he usually plays as a centre. He is particularly known in rugby league and rugby union for his ability to offload the ball in the tackle and, in rugby league, for his shoulder charges.

He started his professional rugby league career with the Canterbury Bulldogs in the Australian NRL. In 2008 he controversially left the Bulldogs mid-season to play rugby union with French club Toulon. In 2010 Williams signed with the New Zealand Rugby Union in an ultimately successful bid to play for the All Blacks at the 2011 Rugby World Cup. He played for Canterbury in the 2010 ITM Cup before being selected for the All Blacks' end of year tour in 2010, making his debut against England at Twickenham. He played for the Crusaders in the 2011 season of Super Rugby and plays for the Chiefs in the 2012 Super Rugby season. He was a member of the All Blacks squad that won the 2011 Rugby World Cup.