Basketball

In early December 1891, Dr. James Naismith, a Canadian-born physical education professor and instructor at the International Young Men's Christian Association Training School (YMCA) (today, Springfield College) in Springfield, Massachusetts, USA, sought a vigorous indoor game to keep his students occupied and at proper levels of fitness during the long New England winters. After rejecting other ideas as either too rough or poorly suited to walled-in gymnasiums, he wrote the basic rules and nailed a peach basket onto a 10-foot (3.05 m) elevated track. In contrast with modern basketball nets, this peach basket retained its bottom, and balls had to be retrieved manually after each "basket" or point scored; this proved inefficient, however, so a hole was drilled into the bottom of the basket, allowing the balls to be poked out with a long dowel each time. The peach baskets were used until 1906 when they were finally replaced by metal hoops with backboards. A further change was soon made, so the ball merely passed through, paving the way for the game we know today. A soccer ball was used to shoot goals. Whenever a person got the ball in the basket, his team would gain a point. Whichever team got the most points won the game. The baskets were originally nailed to the mezzanine balcony of the playing court, but this proved impractical when spectators on the balcony began to interfere with shots. The backboard was introduced to prevent this interference; it had the additional effect of allowing rebound shots. Naismith's handwritten diaries, discovered by his granddaughter in early 2006, indicate that he was nervous about the new game he had invented, which incorporated rules from a children's game called "Duck on a Rock", as many had failed before it. Naismith called the new game "Basket Ball".

The first official game was played in the YMCA gymnasium on January 20, 1892 with nine players. The game ended at 1-0; the shot was made from 25 feet (7.6 m), on a court just half the size of a present-day Streetball or National Basketball Association (NBA) court. By 1897–1898 teams of five became standard.

Measurements and time limits discussed in this section often vary among tournaments and organizations; international and NBA rules are used in this section.
The object of the game is to outscore one's opponents by throwing the ball through the opponents' basket from above while preventing the opponents from doing so on their own. An attempt to score in this way is called a shot. A successful shot is worth two points, or three point if it is taken from beyond the three-point arc which is 6.25 metres from the basket in international games and 23 feet 9 inches (7.2 m) in NBA games.

Games are played in four quarters of 10 (international) or 12 minutes (NBA). College games use two 20-minute halves while most high school games use eight minute quarters. Fifteen minutes are allowed for a half-time break, and two minutes are allowed at the other breaks. Overtime periods are five minutes long. Teams exchange baskets for the second half. The time allowed is actual playing time; the clock is stopped while the play is not active. Therefore, games generally take much longer to complete than the allotted game time, typically about two hours.

Five players from each team (out of a twelve player roster) may be on the court at one time. Substitutions are unlimited but can only be done when play is stopped. Teams also have a coach, who oversees the development and strategies of the team, and other team personnel such as assistant coaches, managers, statisticians, doctors and trainers.

For both men's and women's teams, a standard uniform consists of a pair of shorts and a jersey with a clearly visible number, unique within the team, printed on both the front and back. Players wear high-top sneakers that provide extra ankle support. Typically, team names, players' names and, outside of North America, sponsors are printed on the uniforms.

A limited number of time-outs, clock stoppages requested by a coach for a short meeting with the players, are allowed. They generally last no longer than one minute unless, for televised games, a commercial break is needed.

The game is controlled by the officials consisting of the referee ("crew chief" in men's college and the NBA), one or two umpires ("referees" in men's college and the NBA) and the table officials. For college, the NBA, and many high schools, there are a total of three referees on the court. The table officials are responsible for keeping track of each teams scoring, timekeeping, individual and team fouls, player substitutions, team possession arrow, and the shot clock.

The only essential equipment in a basketball game is the basketball and the court: a flat, rectangular surface with baskets at opposite ends (or in the case of 3-on-3 street basketball, half a court with one basket). Competitive levels require the use of more equipment such as clocks, scoresheets, scoreboard(s), alternating possession arrows, and whistle-operated stop-clock systems.

An outdoor basketball net.

A regulation basketball court in international games is 28 by 15 meters (approx. 92 by 49 ft) and in the NBA is 94 by 50 feet (29 by 15 m). Most courts are made of wood, usually maple. A steel basket with net and backboard hang over each end of the court. At almost all levels of competition, the top of the rim is exactly 10 feet (3.05 m) above the court and 4 feet (1.2 m) inside the baseline. While variation is possible in the dimensions of the court and backboard, it is considered important for the basket to be of the correct height; a rim that is off by but a few inches can have an adverse effect on shooting.

There are also regulations on the size a basketball should be. If women are playing, the official basketball size is 28.5" in circumference (size 6) and a weight of 20 oz. For men, the official ball is 29.5" in circumference (size 7) and weighs 22 oz.
The ball may be advanced toward the basket by being shot, passed between players, thrown, tapped, rolled or dribbled (bouncing the ball while running).

The ball must stay within the court; the last team to touch the ball before it travels out of bounds forfeits possession. The ball is out of bounds if touches or crosses over a boundary line, or touches a player who is out of bounds. This is contrast to other sports such as soccer, volleyball, and tennis (but not rugby or American football) where the ball (or player) is still considered in if any part of it is touching a boundary line.

The ball-handler may not move both feet without dribbling, known as traveling, nor may he dribble with both hands or catch the ball in between dribbles, a violation called double dribbling. A player's hand cannot be under the ball while dribbling; doing so is known as carrying the ball. A team, once having established ball control in the front half of the court, may not return the ball to the backcourt. The ball may not be kicked nor struck with the fist. A violation of these rules results in loss of possession, or, if committed by the defense, a reset of the shot clock.
There are limits imposed on the time taken before progressing the ball past halfway (8 seconds in international and NBA; 10 seconds in NCAA and high school), before attempting a shot (24 seconds in the NBA, 30 seconds in NCAA women's and Canadian Interuniversity Sport play for both sexes, and 35 seconds in NCAA men's play), holding the ball while closely guarded (5 seconds), and remaining in the restricted area (the lane, or "key") (3 seconds). These rules are designed to promote more offense.

No player may interfere with the basket or ball on its downward flight to the basket, or while it is on the rim (or, in the NBA, while it is directly above the basket), a violation known as goaltending. If a defensive player goaltends, the attempted shot is considered to have been successful. If a teammate of the shooter goaltends, the basket is cancelled and play continues with the defensive team being given possession.

These are most commonly committed by defensive players; however, they can be committed by offensive players as well. Players who are fouled either receive the ball to pass inbounds again, or receive one or more free throws if they are fouled in the act of shooting, depending on whether the shot was successful. One point is awarded for making a free throw, which is attempted from a line 15 feet (4.6 m) from the basket.

The referee may use discretion in calling fouls (for example, by considering whether an unfair advantage was gained), sometimes making fouls controversial calls. The calling of fouls can vary between games, leagues and even between referees.
A player or coach who shows poor sportsmanship, for instance, by arguing with a referee or by fighting with another player, can be charged with a more serious foul called a technical foul. The penalty involves free throws (which unlike a personal foul, the other team can choose any player to shoot the free throws) and varies between leagues. Repeated incidents can result in disqualification. Blatant fouls with excessive contact or that are not an attempt to play the ball are called unsportsmanlike fouls (or flagrant fouls in the NBA) and typically will result in ejection.

If a team exceeds a certain limit of team fouls in a given period (quarter or half) – four for NBA and international games – the opposing team is awarded one or two free throws on all subsequent fouls for that period, the number depending on the league. In the US college game if a team surpasses 7 fouls in the half the opposing team is awarded a one-and-one free throw (a player making the first is given a second). If a team exceeds 10 fouls in the half the opposing team is awarded two free throws on all subsequent fouls for the half. A player who, in an international game, commits five fouls (including technical fouls), or in an NBA game, commits six fouls (excluding technical fouls) is not allowed to participate for the rest of the game, and is said to have "fouled out".

After a team has committed a specified number of fouls, it is said to be "in the penalty". On scoreboards, this is usually signified with an indicator light reading "Bonus" or "Penalty" with an illuminated directional arrow indicating that team is to receive free throws when fouled by the opposing team. (Some scoreboards also indicate the number of fouls committed.)

For a player who is fouled while not in the act of attempting a shot, the number of free throws awarded increases with the number of fouls committed. Initially, one shot is awarded, but after a certain number of additional fouls are committed the opposing team may receive (a) one shot with a chance for a second shot if the first shot is made, called shooting "one-and-one", or (b) two shots. If a team misses the first shot (or "front end") of a one-and-one situation, the opposing team may reclaim possession of the ball and continue play. If a team misses the first shot of a two-shot situation, the opposing team must wait for the completion of the second shot before attempting to reclaim possession of the ball and continuing play.
If a player is fouled while attempting a shot and the shot is unsuccessful, the player is awarded a number of free throws equal to the value of the attempted shot. A player fouled while attempting a regular two-point shot, then, receives two shots. A player fouled while attempting a three-point shot, on the other hand, receives three shots.

If a player is fouled while attempting a shot and the shot is successful, typically the player will be awarded one additional free throw for one point. In combination with a regular shot, this is called a "three-point play" or "four-point play" (or more colloquially, an "and one") because of the basket made at the time of the foul (2 or 3points) and the additional free throw (1 point).

Shooting is the act of attempting to score points by throwing the ball through the basket. While methods can vary with players and situations, the most common technique is outlined as follows:

The player faces the basket with feet about shoulder-width apart, knees slightly bent, and back straight. The player allows the ball to rest on the fingertips of the dominant hand (the shooting arm) slightly above the head, with the other hand supporting the side of the ball. To aim the ball, the player's elbow should be aligned vertically, with the forearm facing in the direction of the basket. The ball is shot by extending the bended knees and straightening the shooting arm; the ball rolls off the finger tips while the wrist completes a full downward flex motion. The shooting arm, fully extended with the wrist fully bent, and the fingers pointing downward, is held stationary for a moment following the release of the ball, this is known as a follow-through, which when properly done, enhances the accuracy of the shot. Generally, the non-shooting arm is used only to guide the shot, not to power it.

Players often try to put a steady backspin on the ball to deaden its impact with the rim. The ideal trajectory of the shot is somewhat arguable, but generally coaches recommends a proper arch. Players may shoot directly into the basket or may use the backboard to redirect the ball into the basket.

The two most common shots that use the above described set up are the set shot and the jump shot. The set shot is taken from a standing position, with neither foot leaving the floor, typically used for free throws. The jump shot is taken while in mid-air, when the ball is released near the top of the jump. This provides much greater power and range, and it also allows the player to elevate over the defender. Failure to release the ball before the feet return to the ground is considered a traveling violation.

Another common shot is called the layup. This shot requires the player to be in motion toward the basket, and to "lay" the ball "up" and into the basket, typically off the backboard (the backboard-free, underhand version is called a finger roll). The most crowd-pleasing, and typically highest-percentage accuracy shot is the slam dunk, in which the player jumps very high, and throws the ball downward, straight through the hoop.

Another shot that is becoming common is the "circus shot". The circus shot is a low-percentage shot that is flipped, heaved, scooped, or flung toward the hoop while the shooter is off-balance, airborne, falling down, and/or facing away from the basket.
A shot that misses both the rim and the backboard completely is referred to as an air ball. A particularly bad shot, or one that only hits the backboard, is jocularly called a brick.

Dribbling is the act of bouncing the ball continuously with one hand, and is a requirement for a player to take steps with the ball. To dribble, a player pushes the ball down towards the ground with the fingertips rather than patting it; this ensures greater control.

When dribbling past an opponent, the dribbler should dribble with the hand farthest from the opponent, making it more difficult for the defensive player to get to the ball. It is therefore important for a player to be able to dribble competently with both hands.

Good dribblers (or "ball handlers") tend to bounce the ball low to the ground, reducing the distance of travel of the ball from the floor to the hand, making it more difficult for the defender to "steal" the ball. Good ball handlers frequently dribble behind their backs, between their legs, and switch directions suddenly, making a less predictable dribbling pattern that is more difficult to defend against. This is called a crossover, which is the most effective way to move past defenders while dribbling.

A skilled player can dribble without watching the ball, using the dribbling motion or peripheral vision to keep track of the ball's location. By not having to focus on the ball, a player can look for teammates or scoring opportunities, as well as avoid the danger of having someone steal the ball away from him/her.

A block is performed when, after a shot is attempted, a defender succeeds in altering the shot by touching the ball. In almost all variants of play, it is illegal to touch the ball after it is in the downward path of its arc; this is known as goaltending. It is also illegal to block a shot after it has touched the backboard, or when any part of the ball is directly above the rim.

To block a shot, a player has to be able to reach a point higher than where the shot is released. Thus, height can be an advantage in blocking. Players who are taller and playing the power forward or center positions generally record more blocks than players who are shorter and playing the guard positions. However, with good timing and a sufficiently high vertical leap, even shorter players can be effective shot blockers.