There are a number of types of fouls in an NBA game, but fouls, like other rules in the game, are designed to ensure fair play. They prevent teams and players from using excessive force or illegal means to gain possession of the ball and/or score points. Referees are the agents who make rulings about fouls and enforce the appropriate penalty. Fouls often become a point of contention during games, because they are often subjectively called by the officials. Referees may allow a lot of physical play or call the game very tight, whistling for what can be referred to as "ticky-tack" fouls. Either way, the enforcement of fouls is a significant part of a typical NBA game.
There can be several affects of a foul being called on a player in an NBA game. Each time a foul is called by an official there is a stoppage in play. The team who possessed the ball will take it out of bounds or be awarded a free throw, depending on the type of foul. Each player on the court receives six personal fouls in a game. Once they have received their sixth personal foul they have "fouled out" and can no longer play. A team can commit up to four non-shooting personal fouls in a quarter before two free throws are awarded to the opposing team. Before the fifth foul, the team takes the ball out of bounds from the sideline closest to where the foul was commited. If a foul is committed while a player is shooting, free throws are automatically rewarded, regardless of the number of team fouls. If the shooter makes the shot, the basket counts and the shooter is rewarded a bonus free throw attempt. If the shooter misses, they are awarded two free throws. If the shooter is fouled behind the three-point line, they are awarded three free throw attempts.
One type of foul is a personal foul. According to the NBA rulebook, "A player shall not hold, push, charge into, impede the progress of an opponent by extending a hand, forearm, leg or knee or by bending the body into a posi-tion that is not normal. Contact that results in the re-routing of an opponent is a foul which must be called immediately."
Personal fouls can be committed by an offensive or defensive player and can occur when a player does or does not have the ball. Some typical personal fouls can include: hand-checking (players can not guard another player with their elbow extended), charging (an offensive player knocking over a defender who is stationary), illegal screens (when a player sets a "moving pick" against an opponent, blocking (a defensive player impeeding the progress of an offensive player while moving), and over the back fouls (when one player attempts to grab the ball by reaching over a player who has established position for a rebound.
These types of fouls are the most common in a game. They typically involve contact that is just outside the legal rules of the game and do not involve an attempt to harm another player. Personal fouls result in the opposing team taking the ball out of bounds or attempting free throws.
Another type of foul is a technical foul. These types of fouls can be called for almost reason by the referee at any time. According to the NBA rulebook: "An official may assess a technical foul, without prior warning, at any time. A technical foul(s) may be assessed to any player on the court or anyone seated on the bench for conduct which, in the opinion of an official, is detrimental to the game." Often times, these types of fouls are assessed when a player or coach is upset with a referee and protests a call excessively or verbally assaults the referee. A technical also may be called when a player or coach vents their anger through an inappropriate means, such as punting the basketball or throwing a chair or other object onto the court. Technicals may also be assessed for a delay of game, coaches box violations, defensive three seconds, having less than five players on the floor when the ball is in play, or hanging on the rim. Technicals can also be called for asking for a time-out that a team does not have (the most famous example of this was Chris Webber calling for a timeout his Michigan team did not have during the 1993 NCAA title game.) The result of a technical foul is that the team the foul was committed against is awarded one free throw (shot with no other players in the paint area) and is awarded possession of the ball. A player or coach is ejected from the game upon receiving two technical fouls.
A third type of foul is a flagrant foul. An official typically whistles for this type of foul when a player attempts to harm another player or makes a reckless foul without regard for the basketball. According to the NBA rulebook: "If contact committed against a player, with or without the ball, is interpreted to be unnecessary, a flagrant foul---penalty (1) will be assessed. A personal foul is charged to the offender and a team foul is charged to the team." The result of such a foul is that the opposing team receives two free throws plus possession of the basketball. If the player who was fouled on the play is injured and unable to shoot the free throws, the coach may select a substitute to attempt the shots in their place. A flagrant foul can be assessed whether the ball is dead or alive.Often times, flagrant fouls precede fights in NBA games, as teams attempt to stick up for their teammate(s).
A final type of foul is a double foul. Double personal fouls are rarely called; however double technicals are fairly common. No free throws are awarded on double fouls, whether personal or technical. Double fouls are added to the player's total, but not the team total. If a double foul is called, the team in possession at the time of the call retains possession. If neither team was in possession of the ball, a jump ball at center court occurs.