In basketball, a personal foul is a breach of the rules that concerns illegal personal contact with an opponent. It is the most common type of foul in basketball. A player fouls out on reaching a limit on personal fouls for the game and is disqualified from participation in the remainder of the game.
Players routinely initiate illegal contact to purposely affect the play, hoping it is seen as too minor to be ruled a foul. The threshold is subjective and varies among officials and from game to game. Most contact fouls are not regarded as unsportsmanlike. However, excessive or unjustified contact is penalized more severely. The NBA refers to these as flagrant fouls; other rulebooks call them unsportsmanlike or disqualifying fouls.
History
Basketball has always had the concept of fouls. In 1891, James Naismith's original 13 rules defined a foul as: running with the ball, holding the ball with the arms or body, striking the ball with the fist, shouldering, holding, pushing, striking or tripping in any way of an opponent. Only the fourth definition remains. Running with the ball and striking it with the fist are now violations. Holding the ball with the arms or body is now rare but legal.
Originally, on a player's second foul, the player would be removed without substitution until the next successful goal (similar to a penalty in ice hockey). Before long, free throws were introduced, originally worth three points each, then one. Originally, any team member was allowed to shoot free throws. In 1924, the rules were changed so that the fouled player shot the free throws.
The victim of a contact foul used to be given three attempts at a free throw, and the offense retained possession of the basketball. Now, a player fouled in the act of shooting gets from one to three shots and the other team tends to get possession afterwards (see Penalties below).
Principles
Personal contact does not necessarily constitute a personal foul, unless it gives a player an advantage or puts the opponent at a disadvantage.
Cylinder
In FIBA, the cylinder principle gives each player exclusive rights within an imaginary cylinder defined: in the front by the palms of the hands, when the arms are bent at the elbows so that the forearms and hands are raised, but no farther in front than the feet, in the rear by the buttocks, at the sides by the outside edge of the arms and legs. The cylinder extends from the floor to the ceiling, allowing the player to jump upward.
A player can occupy any cylinder not already occupied by the opponent. No one else is allowed to step or reach into this cylinder. A player must not extend his limbs or bend his body in a way that is not normal. If there is a breach of this principle that places the opponent at a disadvantage, the official may penalise it.
The NBA does not use the cylinder principle to judge contact; it only says that a player may not bend or reach in a position that is not normal (nor push, hold, and so on).
Elements of time and distance
The elements of time and distance concern the reaction time and distance of another person. They apply only to players without the ball, not to the ball carrier. For example, a player cannot suddenly step in front of a sprinting player, even without invading the cylinder. Another example is when a player sets a screen directly behind a player: the player would not physically be able to react to the screen in enough time to avoid it.
Types of foul
Charging and blocking
When significant illegal contact between the ball-carrier and a defender occurs, it usually means that either — The defender committed a blocking foul, or The ball-carrier committed the offensive foul of charging.
Deciding between the two is complex, partly subjective, and often controversial.
Generally, the ball-carrier committed a charge if all of the following are true: The defender was still, or moving sideways or backward but not forward, when contact occurred. The defender took a legal guarding position before the contact, that is, one with both feet on the floor. The defender was hit on the torso (as opposed to the arm or leg).