A sport is a physical activity or game, often competitive and organised, that maintains or improves physical ability and skills. Sport may provide enjoyment to participants and entertainment to spectators. The number of participants in a particular sport can vary from hundreds of people to a single individual.

Sport competitions may use a team or single person format, and may be open, allowing a broad range of participants, or closed, restricting participation to specific groups or those invited. Competitions may allow a "tie" or "draw", in which there is no single winner; others provide tie-breaking methods to ensure there is only one winner. They also may be arranged in a tournament format, producing a champion. Many sports leagues make an annual champion by arranging games in a regular sports season, followed in some cases by playoffs.

Sport is generally recognised as system of activities based in physical athleticism or physical dexterity, with major competitions admitting only sports meeting this definition. Some organisations, such as the Council of Europe, preclude activities without any physical element from classification as sports. However, a number of competitive, but non-physical, activities claim recognition as mind sports. The International Olympic Committee who oversee the Olympic Games recognises both chess and bridge as sports. SportAccord, the international sports federation association, recognises five non-physical sports: chess, bridge, draughts, Go and xiangqi. However, they limit the number of mind games which can be admitted as sports. Sport is usually governed by a set of rules or customs, which serve to ensure fair competition. Winning can be determined by physical events such as scoring goals or crossing a line first. It can also be determined by judges who are scoring elements of the sporting performance, including objective or subjective measures such as technical performance or artistic impression.

Records of performance are often kept, and for popular sports, this information may be widely announced or reported in sport news. Sport is also a major source of entertainment for non-participants, with spectator sport drawing large crowds to sport venues, and reaching wider audiences through broadcasting. Sport betting is in some cases severely regulated, and in others integral to the sport.

According to A.T. Kearney, a consultancy, the global sporting industry is worth up to $620 billion as of 2013. The world's most accessible and practised sport is running, while association football is the most popular spectator sport.