In basketball, a turnover occurs when a player loses possession to the opposing team. This can result from the ball being stolen, the player making mistakes such as stepping out or throwing the ball out of bounds, or committing a violation (such as traveling) or committing an offensive foul.
Some players are prone to turnovers because of having poor court vision or making mental mistakes. Also, many superstars average more turnovers than anybody on their team as they will often be handling the ball. It is unusual for the best player of a team to have zero turnovers. Also, a point guard may often have the most turnovers because they are usually the player that possesses the ball most for their respective team.