A contact sport is any sport where physical contact between competitors, or their environment, is an integral part of the game. For example, gridiron football. Contact may come about as the result of intentional or incidental actions by the players in the course of play. This is in contrast to noncontact sports where players often have no opportunity to make contact with each other and the laws of the game may expressly forbid contact. In contact sports some forms of contact are encouraged as a critical aspect of the game such as tackling, while others are incidental such as when shielding the ball or contesting an aerial challenge. As the types of contact between players is not equal between all sports they define the types of contact that is deemed acceptable and fall within the laws of the game, while outlawing other types of physical contact that might be considered expressly dangerous or risky such as a high tackle or spear tackle, or against the spirit of the game such as striking below the belt or other unsportsmanlike conduct. Where there is a limit as to how much contact is acceptable most sports have a mechanism to call a foul by the referee, umpire or similar official when an offence is deemed to have occurred.

Flag football is a variant of gridiron football where, instead of tackling players to the ground, the defensive team must remove a flag or flag belt from the ball carrier ("deflagging") to end a down. In flag football, contact is limited between players. The sport has a strong amateur following with several national and international competitions each year sponsored by various associations but is most popularly played in America where it was invented. The international governing body for the sport is the International Federation of American Football (IFAF). In 2022, flag football was shortlisted as a proposed discretionary event for the 2028 Summer Olympics in Los Angeles, with inclusion being accepted on October 16, 2023.