Southampton Football Club is an English professional football club based in Southampton, Hampshire, that competes in the EFL Championship, the second tier of English football. Its home ground since 2001 has been St Mary's Stadium, before which it was based at The Dell. The team play in red and white shirts. They have been nicknamed "The Saints" because of the club's beginnings as a church football team at St Mary's Church. Southampton shares a long-standing South Coast derby rivalry with Portsmouth, in part due to geographic proximity and both cities' respective maritime histories.

Football is the most popular sport in England, where the first modern set of rules for the code were established in 1863, which were a major influence on the development of the modern Laws of the Game. With over 40,000 association football clubs, England has more clubs involved in the code than any other country. England hosts the world's first club, Sheffield F.C.; the world's oldest professional association football club, Notts County; the oldest national governing body, the Football Association; the joint-oldest national team; the oldest national knockout competition, the FA Cup; and the oldest national league, the English Football League. Today England's top domestic league, the Premier League, is one of the most popular and richest sports leagues in the world, with five of the ten richest football clubs in the world as of 2022.