A ball that is not in the possession of a player and that is considered live and able to be recovered by either team. Typically these occur after a fumble by an offensive player, and there will be a scramble as both teams attempt to recover the ball. The ball is considered loose until 1) it is recovered by a player from either team or 2) it goes out of bounds. A loose ball is fair game for any player on the field of play to recover, regardless of eligible receiver status. A loose ball recovered by the defense is a turnover.
A loose ball is a free opportunity for all players to recover the ball. While most often they are caused by fumbles, they can also be caused by a backwards pass or lateral that is not caught by an offensive player. A loose ball is often a scramble due to the irregular shape of the football, since the ball will bounce around unpredictably. Players will either try to pick the ball up and run with it, or fall on it to gain possession. Picking the ball up is a higher-risk play because the player has the potential to bat the ball away in the attempt to pick it up, thus giving other players the opportunity to recover it.