In basketball, two teams of five players each compete on a rectangular indoor court, each team trying to score the most baskets within the time limit. Dr. James Naismith invented the sport in 1891 in Springfield, Massachusetts. The National Basketball Association, or NBA, founded in 1946, serves as the governing body for men's professional basketball in North America.
Scoring
Shots made on or inside the three-point line earn the shooter's team two points. Shots made outside the three-point line earn three points. In the NBA, the three-point line runs in an arc that's 23 feet, 9 inches from the middle of the basket and then parallel to the sides and 3 feet from the sidelines. The free throw line runs parallel to the end line and 15 feet from it. Free throw shots earn one point. For a player to earn three points for a shot, he must have at least one foot on the floor outside the three-point line before the shot, and he may not be touching the floor on the line or inside the line.
Timing
NBA basketball games consist of four 12-minute quarters. Officials time a 130-second break between the first and second periods and between the third and fourth periods, and a 15-minute break between halves. Overtime periods last five minutes. Periods end when time expires, unless a live ball is in flight, in which case the period ends when the goal is made or missed.
Shot Clock
A 24-second shot clock begins each time a team gains possession of the ball. The team must attempt a field goal before this time expires. The team's possession of the ball ends with a legal field goal attempt or when the opposing team gains possession. In both cases, the 24-second clock begins again. If the team in possession of the ball does not attempt a shot before time runs out, the opposing team gains possession of the ball at the sideline nearest to the point where play was suspended, but no closer to the baseline than the imaginary extension of the free throw line.
Free Throws
Free throw shooters must stand behind the free throw line and inside the upper half of the free throw circle. During free throws awarded after a personal foul, members of the opposing team must occupy the two the spaces nearest the end line. Two of the free throw shooter's teammates must occupy the next two spaces. A third opponent may occupy one of the third spaces. All players who do not occupy a space in the free throw lane must remain behind the three-point line during the shot. The player has 10 seconds to make his free throw attempt after the official gives him the ball.
Violations
Common rules violations include putting the ball out of bounds, running with the ball without dribbling it and beginning a second dribble after voluntarily ending the first. All of these violations result in loss of ball possession. Players must not kick the ball or strike the ball with a fist. Officials penalize personal fouls, such as holding, pushing, charging or impeding an opponent's progress, by awarding free throws to the fouled player. If a player commits six personal fouls in a game, he cannot play for the rest of the game. More serious conduct violations or fighting fouls may result in technical fouls and/or fines.
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