The referees maintain orderly and fair play on the court and administer the rules of the game to ensure that neither team has an unfair advantage.

To make appropriate calls, referees must be observant and have exceptional knowledge of rules and playing styles. Referees must position themselves during play to afford a clear view of the action without interfering. A referee will cite rules infractions and stop play by blowing a whistle. After play has stopped, referees signal what violation has occurred by using hand signals and a verbal call. Most referees' decisions must be made very quickly. During the game a referee can run several miles supervising the activity, so exceptional physical fitness is important. Between games and during the off-season, referees engage in a continuing study of all possible game situations.

Whether basketball is played informally on playgrounds or in organized fashion in leagues, it is played with essentially the same set of rules, which have stayed generally consistent since the game's invention in 1891. The game involves two five-player teams that play both offense and defense. At the completion of each game, the team that has scored the most points wins. Recreational and high school games last 32 minutes (four quarters of 8 minutes each), college and international games last 40 minutes (two halves of 20 minutes each), women's professional games last 40 minutes (either two 20-minute halves or four 10-minute quarters, depending on the league), and men's professional games last 48 minutes (four quarters of 12 minutes each). When a game is tied after regulation time has ended, the teams play overtime periods until one team ends an overtime period with more points and is therefore the winner.

Every game begins with a jump ball at the center of the court. With one player from each team lined up in the midcourt circle, a referee tosses the ball high into the air, and the two players attempt to direct the ball to one of their own teammates. The team that gains possession plays offense, and the opposition plays defense, protecting its own basket until it regains possession of the ball. The offensive team has a set time, usually 35 seconds or less (depending on the level of competition), to score by putting the ball through the opposition's basket. (Scoring a basket is also known as scoring a field goal or a hoop.) The time to shoot is measured by a shot clock positioned in the arena for easy viewing from the court. An offensive player cannot run or walk with the ball without dribbling (bouncing the ball against the ground). The ball may also be advanced by passing it to a teammate. Once a player stops dribbling, the ball must be shot, passed to a teammate, or touched by another player before the first player can regain the ball and dribble again.

A team's offense can be sophisticated, involving specific diagrammed plays that are intended to make offensive play more efficient and defensive play more difficult. There are two ways an offensive team can score points. The first way to score is to make a basket, which is worth 2 or 3 points, depending on the distance of the shot. The second way to score is a foul shot, also called a free throw. These are awarded to a player when the opposition commits a personal foul (illegal contact such as pushing, holding, charging, or tripping) or a technical foul (violation of the rules without physical contact, such as unsportsmanlike conduct). When a foul occurs during a shot, the referee blows a whistle and the player that was fouled is awarded one, two, or three shots, depending on whether the shot scored despite the foul and according to where the infraction occurred. Each foul shot is taken from the free-throw line, 15 ft (4.6 m) from the basket, without opposition, and is worth one point.

Possession of the ball alternates when the offense scores or when the defense is successful in preventing a basket and regains the ball in the process. Specific defensive game plans are often created to make scoring more difficult. A good defense will often force the offense to miss a shot or to lose possession of the ball—for example, by committing an offensive foul or by failing to shoot the ball in the allotted time. Defenses can also gain possession of the ball by intercepting a pass or by stealing the ball from the dribbler. When an offensive team misses a shot, the ball is free, and both teams have an equal opportunity to retrieve the ball. This is called making a rebound. Play continues as the teams score and possession changes. A time-out, when the game is stopped for a certain amount of time, allows coaches to instruct players or to develop a new game strategy.

Playing offense is perhaps the most prominent part of playing basketball, as it allows players to demonstrate and improve upon individual skills necessary to being successful. Many of basketball's best players have exceptional talents on offense. Basic offensive skills are passing, ball handling, shooting, and rebounding.

Passing the basketball is the fastest and often the most efficient way of advancing the ball up the court. A team that passes well will be able to take uncontested shots, to score easy baskets by moving the ball up the court quickly, and to prohibit the defense from initiating its own game plan. There are five types of passes: chest, in which the ball is thrown from chest height; bounce, in which the ball is bounced on the ground on its way to the teammate; overhead, in which the ball is thrown with both hands extended over the head; baseball-style, in which the ball is thrown like a baseball; and behind-the-back, in which the player throws the ball at waist height with one hand whipping the ball around the back. All of these passing styles are used during the course of a game.

Many of basketball's best players are also adept at ball handling. To be a good ball handler, a player must watch the action on the court, keeping the eyes straight ahead and not focused down on the floor. The player must also keep the ball low, protecting it from defenders and bouncing it no higher than the waist. Good ball handlers can use either hand to dribble effectively and can change directions quickly. There are five types of dribbling styles: speed, in which the ball is dribbled while the player is moving; crossover, in which the ball is bounced and crossed from one hand to the other in front of the body; behind-the-back, in which the ball is bounced and crossed behind the back; between-the-legs, in which the ball is bounced and crossed between the legs; and spin, in which the ball is bounced and crossed while the player spins away from the defender.

From the elementary school level to the professional leagues, shooting is the most important part of basketball. There are many types of shooting forms, the basic being the layup, the jump shot, the foul shot, and the hook shot. The layup is the easiest shot in basketball, taken right under the basket using either hand. Over the years, the dunk shot, a different style of layup in which the ball is slammed forcibly through the basket, has become one of basketball's most exciting shots. The jump shot is taken when the shooter leaps in the air and at the top of the jump releases the ball toward the basket. The foul shot is an uncontested shot taken from the free-throw line following a foul. A hook shot is taken when the shooter turns sideways to the basket, places his or her body between the ball and the defender, and releases the ball over his or her head in a high arc toward the basket.

When a shooter misses a shot, the team that retrieves the ball has recovered a rebound. When a member of the offensive team recovers the rebound, the offensive team regains possession and the shot clock starts over. When the defensive team recovers the rebound, it then plays offense. Strength, natural instinct, and good positioning and timing are important to good rebounding.

Playing good offense requires strategic decisions. One style of offense is to use set patterns to get uncontested shots. The most important technique of a so-called slow-down offense is setting screens. This occurs when offensive players position themselves in a way that impedes the defenders' movement. The screen is often accompanied by the give-and-go, in which one player passes to a teammate and then moves across the court, usually toward the basket in a position to receive a return pass immediately. In comparison to the slow-down offense, a fast-break offense involves quick shots as the ball is either dribbled or passed up the court rapidly.

Defense is just as important to winning basketball games as offense. The goal of defense is simple: to stop the opposition from scoring. The more times a team stops an opponent from scoring, the more likely it is that a victory will be secured. The basic defensive technique involves guarding the opponent while keeping both feet at least shoulder-width apart, with one foot slightly ahead of the other and the knees bent. When defending, a player's weight should be placed on the balls of the feet to ensure quick movement in any direction.

General defensive positioning involves skilled movement. A defensive player should take short, quick shuffle steps when moving side-to-side. Crossing one foot over another is improper defensive technique. Defenders want to force opponents away from the basket and limit the ability to dribble the ball toward the basket. Good defenders use quickness to steal or intercept the ball and are cautious not to foul. One part of playing strong defense is blocking the opposition's attempted shot, because good shot-blocking teams make opponents hesitate about shooting. When defending an opponent who doesn't have the ball, the general rule is to stay between that player and the basket being defended. Good defenders also play team defense, working together and verbally communicating among themselves to ensure that the offense doesn't obtain an easy shot.

There are two types of basic defensive team play, man-to-man defense and zone defense. In man-to-man defense, each player guards a specific opponent, usually one that plays the same position, so that a guard defends a guard, a forward defends a forward, and so on. In a zone defense, each player guards a specific area of the court. The most widely used zone defense is called a 2-1-2 zone, in which the two guards cover the forefront of the defense, the center guards the middle portion of the court, and the two forwards defend the area nearest the basket. A good 2-1-2 zone defense makes it difficult to pass the ball from near the basket back outside, hampers teams from initiating a smooth offense, and is effective in slowing down a fast-break style of offense. Zone defense used to be illegal in the National Basketball Association (NBA), but the league changed its rules in 2001 to allow it.

While basketball gains much of its popularity through spectators watching professional competition, the sport flourishes worldwide at amateur levels for both men and women. Most organized amateur play takes place at the high school and college level, where the season runs from November through March.

High school basketball's governing body, the National Federation of State High Schools (NFHS), is located in Indianapolis, Indiana. The NFHS does not crown a national champion. Instead, high school teams compete to win their state championship, with each state having its own guidelines for determining titles. Most states have several state champions, each in a category determined by school size.

The National Collegiate Athletic Association (NCAA), located in Indianapolis, is the most important organization governing major college competition. The National Association of Intercollegiate Athletics (NAIA), located in Tulsa, Oklahoma, oversees competition for smaller four-year schools. The National Junior College Athletic Association (NJCAA), located in Colorado Springs, Colorado, governs play for two-year and community colleges throughout the country. Under the jurisdiction of these national governing bodies are individual conferences and leagues. Well-known NCAA conferences include the Atlantic Coast and the Big East, on the East Coast; the Big Ten, in the Midwest; and the Pacific-10, in the West.

The NCAA, the NAIA, and the NJCAA all sponsor postseason national championship tournaments. The men's and women's NCAA national championship basketball tournaments are the most high-profile of these tournaments. They are also two of the premier sporting events in the United States. Both tournaments are held in March and early April, using the same format to determine a national champion. Each tournament involves 64 teams in a single-elimination competition, meaning that one loss disqualifies a team from further play.

The selection process for deciding which teams will participate in the tournament is complex. Teams are invited to the tournament either as automatic qualifiers or as at-large teams. Automatic qualifiers gain admission by winning their conference tournament at the end of the season, or if the conference does not hold a tournament, by finishing the season with the best conference record. After the automatic qualifiers are determined, a special committee fills out the 64-team field by choosing at-large teams, using a number of factors. These include a team's final record for that season, its performance in past championship tournaments, and the Ratings Percentage Index (RPI), which uses statistics to analyze the team's strengths compared to other teams. In some years, such as in 2001, the tournament will choose several schools to play special qualifying games to fill out the field.

The 64 teams are placed into four regional tournaments: East, West, South, and Midwest in men's play; East, Mideast, Midwest, and West in women's play. The 16 teams assigned to each regional draw are a mix of colleges and universities from across the country. In each region they are seeded, or ranked, from 1 to 16 according to their strength and season schedule (with the 1 seed the strongest team). A seeded team assigned to a specific region should be on par with its corresponding seed in the other three regional draws. For example, a team ranked as the 10 seed in the Midwest regional draw should be of equal strength to the 10 seed in the East regional draw.

In each region, the higher ranked teams play the lower ranked teams: the 1 seed plays the 16 seed, the 2 seed plays the 15 seed, and so on. Winning teams advance and continue to play until only one unbeaten team remains. This team then advances to the Final Four, the national semifinals. There is no seeding in the Final Four. Instead, it is predetermined which two regional winners will meet in each semifinal game. The championship game pits the victors of these two games against each other. The team that triumphs in the Final Four is crowned the national champion.

Fan support is intense throughout the tournament, and visiting fans provide an economic windfall for the various cities hosting tournament games. Cities therefore bid for the right to host games, and the sites are chosen several years in advance to allow the cities time to prepare for the tournament. The tournament has produced a unique vocabulary over the years. The excitement generated is referred to as March Madness, while the entire event is often called the Road to the Final Four or the Big Dance.

In the men's tournament, the University of California, Los Angeles (UCLA) has won the championship 11 times, with John Wooden coaching UCLA to 10 of those victories. The University of Kentucky has 7 championships, and Indiana University has 5. Other teams that have had a significant impact during the tournament's history include the University of North Carolina, the University of Louisville, and Duke University. The University of Tennessee has dominated the women's NCAA tournament. Coached by Pat Summitt, Tennessee has won six titles since the women's tournament began in 1982. Several other schools—the University of Southern California (USC), the University of Connecticut, Stanford University, and Louisiana Tech University—have won two titles each.

Although the NCAA tournament is the most widely recognized of collegiate postseason tournaments, the National Invitation Tournament (NIT) is the oldest and was originally the most prestigious. The NIT was first held in 1938, with Temple University winning. At first, college teams could compete in both the NIT and the NCAA tournament. Beginning in the 1950s, however, teams began participating in either the NIT or NCAA tournament, based on their season record, with the better teams generally accepting invitations to the NCAA tournament. This tendency became stronger over time, and now the NCAA tournament winner is regarded as the national collegiate basketball champion. The NIT, however, remains an important postseason activity for teams that do not qualify for the NCAA tournament. The City College of New York (CCNY) is the only school to win both the NIT and the NCAA tournament in the same season, accomplishing this feat in 1950. Shortly after this the rules were changed to make it impossible for a team to play both tournaments.

The highest level of professional play takes place in the United States and Canada, and players from all over the world strive to play in North America. But professional basketball is also played in more than 20 other countries. Brazil, Japan, Germany, France, and Spain are among the nations that support leagues that develop the skills of international players. Some players from the United States and Canada play professional basketball in other countries if they fail to make teams in their own countries.

The National Basketball Association (NBA), with teams from the United States and Canada, is the major professional basketball league in the world.

The 29 NBA teams are divided into two conferences, the Eastern and Western, each of which has two divisions. Each NBA team conducts a training camp in October to determine its 12-player roster. Training camp allows each team to evaluate players, especially rookies (first-year players), to assess the team's strengths and weaknesses, and to prepare players for the upcoming season through a series of on-court drills and practice of offensive and defensive strategy. After a series of exhibition games, the NBA begins its 82-game regular season in the first week of November.

In February the NBA interrupts its season to celebrate the annual NBA All-Star Game, featuring the game's best players as selected by the general balloting of fans throughout the United States and Canada. After the NBA season concludes in April, a total of 16 teams qualify for the playoffs (8 teams from each conference). In each conference the two division winners are guaranteed a playoff spot. The remaining playoff spots in each conference are awarded on the basis of win-loss records to the six next-best teams, regardless of division. The playoffs start with the teams with better records playing the teams with worse records in a best-of-five series, in which the winner is the first team to win three games. In subsequent rounds best-of-seven series are played, with the first team to earn four victories winning the round. The playoffs continue in this elimination scheme until a conference champion is crowned. The champions from the Eastern and Western conferences then meet in a best-of-seven series to determine the NBA champion.

Every June the league conducts its amateur draft, in which teams obtain the rights to the best available players in the world. Any player whose high school class has graduated and who is at least 17 years old qualifies for the NBA draft if that player renounces his collegiate eligibility by mid-May. Generally, players attend at least one year of college before turning professional, although beginning in the 1990s a few high school players have entered the draft each year.

To determine the draft order the NBA uses a draft lottery, introduced in 1985. Those teams that failed to qualify for the playoffs the previous season are eligible for the lottery. The lottery determines the first three teams to select in the draft. The remaining teams, including those that qualified for the playoffs the preceding season, draft according to their win-loss record of the previous season, so that teams with poorer records draft earlier than those with better records. Teams may trade draft picks with each other, either for different picks or for players. The NBA draft consists of only two rounds, with a total of 58 players chosen. Those players not selected in the draft can be invited to try out for a team and are sometimes signed as free agents.

Although many players go straight from college or overseas leagues into the NBA, the league also supports developmental leagues that allow players, coaches, executives, and referees to hone their skills. One such minor league was the Continental Basketball Association (CBA), founded in 1946 as the Eastern Professional Basketball League. The CBA was financially unstable, however, and folded in early 2001 after NBA executives decided to start their own minor league. The National Basketball Development League (NBDL) is scheduled to begin its first season in November 2001 and will consist of eight teams based in small cities throughout the southeastern United States.

During the 1990s women's basketball became increasingly popular in North America, and two professional women's leagues started play. The now-defunct American Basketball League (ABL) was founded in 1996, and the Women's National Basketball Association (WNBA) was founded in 1997. One major reason these leagues were formed was to bring the nation's top female players back to the United States. With no professional league in the United States, many of the former college stars had been competing in foreign leagues.

The ABL began play in the fall of 1996 with eight teams divided between two conferences. The addition of expansion team franchises in 1997 and 1998 brought the league to a total of ten teams. The ABL played a 44-game regular season from October to February, followed by playoffs and a championship series. The Columbus Quest won the league championship in the first two years of ABL competition (1996-97 and 1997-98). In December 1998, midway through the ABL's third season, the league filed for bankruptcy, ended its season, and disbanded its franchises. Some ABL players were absorbed into the WNBA through a draft.

The top women's league in the United States is the WNBA. It was founded by the NBA and is collectively owned by the 29 NBA franchises. All WNBA teams are located in cities that also house NBA teams. In addition, some of the team names are related to the names of NBA teams. For example, the Washington Mystics play in Washington, D.C., home of the NBA's Washington Wizards; and the Utah Starzz play in Salt Lake City, home of the NBA's Utah Jazz.

In 2000 the WNBA added four expansion team franchises—the Indiana Fever, the Miami Sol, the Portland Fire, and the Seattle Storm—which brought the league to a total of 16 teams, divided between two conferences. The league plays a 32-game regular season during the summer, and eight teams qualify for the playoffs. The Houston Comets won the first four WNBA championships, in 1997, 1998, 1999, and 2000. The league sponsors a yearly All-Star Game and holds an annual player draft in April.

While basketball is extremely popular in the United States, it is also growing in other countries. There are more than 200 national federations that belong to Fédération International de Basketball Association (FIBA; French for “International Basketball Federation”), an independent organization that governs international basketball. FIBA, established in 1932 and headquartered in Munich, Germany, divides the world into five sections, called zone commissions. These commissions—Africa, Asia, the Americas, Europe, and Oceania—govern basketball within their regions and conduct their own championships.

In international basketball both men and women compete on club teams in leagues within their national federations. The top professional league in each country is called the first division, and teams in the first division compete for several national and international championship titles. Most international leagues allow two foreign players on their rosters. The international game is similar to American basketball, with some exceptions. For example, the size and shape of the key (the area underneath the basket bordered by the free-throw line and the foul lanes) is in a trapezoidal shape, wider near the baseline. This makes it distinct from the rectangular shape in American basketball.

Several international basketball stars have been inducted into the Basketball Hall of Fame, including Sergei Belov of Russia, Uljana Semjonova of Latvia, and Kresimir Cosic of Croatia. Players from anywhere in the world are eligible to play in the NBA, and European players were first drafted by NBA teams in 1989. In the 1990s many foreign players, such as Vlade Divac and Toni Kukoc from the former Yugoslavia and Arvydas Sabonis of Lithuania, had success in the NBA.

Every four years, the worldwide basketball community gathers for competition at the Olympic Games. Olympic play for men was first introduced as a demonstration sport (with no medal awarded) at the 1904 games in St. Louis, Missouri. The first official Olympic basketball tournament was held at the 1936 Games in Berlin, Germany. The 1936 contests were held outdoors in a tennis stadium on courts of clay and sand. The United States team won the Olympic gold medal that year, defeating the Canadian team by a score of 19-8 in the final round. The score was so low because the courts were soaked from rain, making it difficult for the players to maintain footing and to dribble.
The United States dominated early Olympic basketball competition, winning the first seven gold medals. In 1972, however, the team from the Union of Soviet Socialist Republics (USSR) snapped the 62-game Olympic winning streak of the United States to capture the gold medal on a controversial basket at the buzzer. Subsequently, the United States remained strong, using teams of primarily college stars to win in 1976 and 1984. But teams from the USSR, which won in 1988, and Yugoslavia, which won in 1980 and finished second in 1976 and 1988, were also successful in Olympic competition.

In 1992 professional players were first allowed to compete in the Olympics, and USA Basketball (the governing body of Olympic basketball in the United States) assembled a national team made up of the NBA's best players. Known as the Dream Team, this squad overwhelmed its competition, winning the gold medal easily. At the 1996 Olympics in Atlanta, Georgia, the American professional players again dominated competition, and the United States took another gold medal. At the 2000 Olympics in Sydney, Australia, the United States also won gold but did not dominate play as thoroughly as before.

Women's Olympic basketball competition began at the 1976 Games in Montréal, Québec, Canada, with the Soviet team winning. The U.S. team captured its first gold medal at the 1984 Games in Los Angeles. The success of the gold-medal-winning American squad at the 1996 Olympics generated increased interest in women's basketball in the United States. All of the players from that squad went on to play in the ABL or WNBA. The United States repeated as gold medal champions at the 2000 Olympics. Other countries with successful traditions in Olympic women's basketball include Australia, Brazil, China, and the former Yugoslavia.

In addition to the Olympics, other international championships include the world championships, played every four years; the European championships, held annually; the championships at the Pan American Games, played every four years; and the Jones Cup, held annually for the top club teams from around the world.

In early December 1891, Luther Gulick, chairman of the physical education department at the School for Christian Workers (now Springfield College) in Springfield, Massachusetts, instructed physical education teacher James Naismith to invent a new game to entertain the school's athletes during the winter season. With an ordinary soccer ball, Naismith assembled his class of 18 young men, appointed captains of two nine-player teams, and introduced them to the game of Basket Ball (then two words). Naismith, who had outlined 13 original rules, dispatched the school janitor to find two boxes to be fastened to the balcony railing at opposite sides of the gymnasium, where they would serve as goals. The school janitor, however, only found two half-bushel peach baskets, and the game was played with these.

The soccer ball and the peach basket soon gave way to specialized equipment.

For example, in the early days the peach baskets were closed at the bottom, meaning that someone had to climb on a ladder to retrieve the ball after a made basket. The peach basket was later replaced by a metal rim with a net hanging below, and in 1906 people began opening the netting to let the ball fall through. The first basketballs were made from panels of leather stitched together with a rubber bladder inside. A cloth lining was added to the leather for support and uniformity. The molded basketball, introduced in about 1942, was a significant advancement for the sport. The molded ball, a factory-made ball that had a constant size and shape, offered better reaction and durability, making play more consistent and the development of individual skills easier. In Naismith's original 13 rules, the ball could be batted in any direction with one or both hands, but it could not be dribbled because players could not move with the ball. Beginning in 1910 a player could dribble the ball, but could not shoot after dribbling. It was not until 1916, following heated debate, that players were allowed to shoot after dribbling.

Throughout basketball's history, no part of the game has been more monitored than the act of fouling an opponent. In basketball's early days, a player's second foul would mean removal from the game until the next field goal was made. If a team committed three consecutive fouls, the opposition would be awarded a field goal. Beginning in 1894 players were given a free throw when fouled. Beginning in 1908 players who committed five fouls were disqualified from the game. Based on the severity of the foul, the rules were soon amended so that players were awarded either two shots or one shot plus a bonus shot, which was attempted only if the first shot was made. The rules also determined that an offensive player could commit a foul by playing too aggressively.

In 1892 Lithuanian-born physical education teacher Senda Berenson Abbott introduced basketball to women, at Smith College in Northampton, Massachusetts. Because it was believed that Naismith's version of the game could be too physically demanding for women, Berenson Abbott made the following changes to the game: The court was divided into three equal sections, with players required to stay in an assigned area; players were prohibited from snatching or batting the ball from the hands of another player; and players were prohibited from holding the ball for longer than three seconds and from dribbling the ball more than three times.

Basketball's growth spread in the United States and abroad through Young Men's Christian Associations (YMCAs), the armed forces, and colleges.
Due to its simple equipment requirements, indoor play, competitiveness, and easily understood rules, basketball gained popularity quickly. In May 1901 several schools, including Yale and Harvard universities and Trinity, Holy Cross, Amherst, and Williams colleges, formed the New England Intercollegiate Basketball League. The development of collegiate leagues and conferences brought organization and scheduling to competition, and formal league play created rivalries. More importantly, collegiate leagues became a critical training ground for officials.

By the early 1900s basketball was played at about 90 colleges—most of them located in the East and Midwest. In 1905 teams from the University of Minnesota and the University of Wisconsin traveled to New York to challenge Eastern League champion Columbia University. Columbia's “Blue and White Five” defeated both Midwestern teams, and the idea of an intercollegiate championship was born. By 1914 more than 360 colleges offered basketball, and the sport had spread heavily into the Midwestern states.

In 1915 the Amateur Athletic Union of the United States (AAU), the NCAA, and the YMCA formed a committee to standardize rules, and during the next ten years a number of regional conferences were formed. Games between top regional teams were sometimes awarded national champion status by the press, but an official championship tournament was still many years away. Travel and scheduling difficulties and continued regional rule differences slowed the organization of a tournament that could impartially produce a national champion.

The first national collegiate tournament was held in Kansas City, Missouri, in 1937. The teams in this tournament, however, were all from the Midwest. New York, with a large fan base that generated travel funds, was the site of the NIT tournament, which was the first truly national collegiate tournament. The first NIT was held at the end of the 1937-38 season.

The NIT was promoted by members of the Metropolitan Basketball Writers Association—a New York City sportswriters' group. In 1939 a group of coaches from the National Association of Basketball Coaches (NABC), fearing Eastern bias, organized and sponsored the first NCAA national tournament. In this tournament the University of Oregon defeated Ohio State University. The NCAA took sole control of the organization of its tournament after that first year. For the next decade, the NCAA and NIT tournaments competed to become the universally recognized national championship tournament, with the NCAA eventually winning out.

The NCAA tournament's original format, used for its first 12 years, divided the country into eight districts, each with a regional selection committee sending a team to the eight-team tournament. As the tournament gained importance, the field gradually enlarged to its present size of 64, made up of champions from a number of conferences, in addition to other successful teams.

Professional basketball began in 1896 at a YMCA in Trenton, New Jersey. A dispute between members of the YMCA team and a YMCA official led to the players forming a professional team and playing for money. In 1898 a group of New Jersey newspaper sports editors founded the National Basketball League (NBL). The NBL consisted of six franchises from Pennsylvania and New Jersey. Stars of this league included Ed Wachter, who played in about 1,800 professional games, and Barney Sedran, who played on 10 championship teams in 15 years.

The Buffalo Germans, a team that won 111 straight games between 1908 and 1911, and the Original Celtics, a team that pioneered many tactics in basketball, including the development of the zone defense, were extraordinarily successful professional teams in the early 20th century. The first successful national professional league was the American Basketball League (ABL), which lasted from 1925 to 1931. The New York Renaissance, a team made up of black players, dominated the 1930s. The Rens, as the team was called, were the best team of the era, winning 88 consecutive games during one stretch. Another all-black team with similar success was the Harlem Globetrotters. The Globetrotters were founded in 1927 as a competitive team, but through the years they became known for their basketball acrobatics and humorous routines.

Although most basketball players were men, 37 states offered high school varsity basketball for women by 1925, and in 1926 the AAU formed a national tournament for women's teams. This enabled women to showcase their basketball skills after scholastic play was finished, and also to gain employment at companies that sponsored their own AAU teams. Notable players from this era of women's basketball include Babe Didrikson, Alline Banks Sprouse, and Nera White, who was one of the first two female players elected to the Basketball Hall of Fame. In 1938 the three-court game was changed to a two-court game, with six players on a team (three on offense and three on defense). Players were still prohibited from straying from their assigned areas.

In the mid-1930s another professional league called the National Basketball League (NBL) was founded, taking the same name as the earlier NBL, which had ceased operation some years before. In 1946 a group of executives in New York City formed yet another new professional basketball league, known as the Basketball Association of America (BAA). This new circuit was a direct competitor with the new NBL, with teams in New York City; Boston, Massachusetts; Philadelphia, Pennsylvania; Chicago, Illinois; and Detroit, Michigan. Just before the 1948-49 season, the four strongest teams in the NBL—those from Minneapolis, Minnesota; Rochester, New York; Fort Wayne, Indiana; and Indianapolis, Indiana—joined the BAA. The following season, the NBL's six surviving teams also joined the BAA, forming a three-division league that was renamed the National Basketball Association (NBA). After the 1949-50 season the NBA reduced its size and established two divisions, the forerunners to the Eastern and Western conferences that were established after the 1969-70 season.

In the late 1940s and early 1950s, the Minneapolis Lakers, led by center George Mikan and coached by John Kundla, won five NBA championship titles (1949, 1950, 1952-1954). In the 1950s guard Bob Cousy and forward Bob Pettit had the greatest individual impact on professional basketball. Cousy, nicknamed the Houdini of the Hardwood because of his ball-handling skills, led the NBA in assists eight straight years (1953-1960) and guided the Boston Celtics to six NBA titles (1957, 1959-1963). Pettit finished his career with a remarkable 26.4 points per game (ppg) average while leading the St. Louis Hawks to appearances in the NBA championship finals in 1957, 1958, 1960, and 1961, with the Hawks winning the title in 1958.

The Celtics dominated the NBA from 1957 to 1969. During this 13-season period, the team, coached mostly by Red Auerbach, won 11 NBA titles (1957, 1959-1966, 1968, 1969), including 8 consecutively. The Celtics had many stars, but center Bill Russell was arguably the greatest. In his 13-season career Russell averaged 15.1 ppg and 22.5 rebounds per game (rpg). Another dominant center of the time was Wilt Chamberlain. Chamberlain played for the Philadelphia Warriors, San Francisco Warriors (the team moved west in 1962), Philadelphia 76ers, and Los Angeles Lakers. He scored 100 points in a single game in 1962 and averaged 50.4 ppg for the 1961-62 season. Neither record has ever been approached by another player. Top guards of the 1960s included Oscar Robertson of the Milwaukee Bucks, Jerry West of the Los Angeles Lakers, and Walt Frazier of the New York Knicks.

The University of California, Los Angeles dominated college basketball from 1963 to 1975. Coached by John Wooden, UCLA won ten national championships during this time (1964, 1965, 1967-1973, 1975), including seven consecutively. From 1971 to 1974, UCLA won 88 consecutive games, an NCAA record. Wooden's UCLA teams featured great players such as center Bill Walton, guard Gail Goodrich, forward Jamaal Wilkes, and forward Marques Johnson. The best player to emerge from UCLA was center Kareem Abdul-Jabbar, who was born Lew Alcindor. Abdul-Jabbar led UCLA to three straight NCAA titles from 1967 to 1969. As a professional he led the Milwaukee Bucks to an NBA title in 1971, and he led the Los Angeles Lakers to five NBA titles in the 1980s (1980, 1982, 1985, 1987, 1988). Known for his famous sky-hook shot, Abdul-Jabbar played 20 seasons in the NBA and retired as the league's leading career scorer, with 38,387 points. 

For two decades after its founding, the NBA was the only major professional basketball league. But in 1967 the American Basketball Association (ABA) was formed. The league became known for the flashy playing style it encouraged and the distinctive red, white, and blue basketballs it used. The ABA convinced several NBA players to switch leagues, often for lucrative contracts. Probably the best player in the ABA was guard and forward Julius Erving, who later starred in the NBA. The ABA disbanded in 1976, with several of its teams joining the NBA.

In the late 1970s, the NBA experienced difficulty: The game was perceived as dull, the league's ticket sales decreased, revenue declined, and television ratings were as low as they had ever been. In March 1979, however, two collegiate players, forward Larry Bird of Indiana State University and guard Magic Johnson of Michigan State University, helped revive public interest in basketball. The two players, the stars of their teams, faced each other in the 1979 NCAA championship game, won by Michigan State. Both players went on to have distinguished NBA careers. In the 1980s Bird helped revitalize the Boston Celtics franchise, leading the team to three NBA titles (1981, 1984, 1986). Johnson did the same in Los Angeles, as he and Abdul-Jabbar guided the Lakers to five NBA championships.

In the late 1980s the Detroit Pistons emerged as a powerhouse team, featuring stars such as guard Isiah Thomas and forward Dennis Rodman. Detroit reached the NBA Finals in 1988, 1989, and 1990, capturing the title during the latter two years. Increased interest in the professional game carried over to collegiate basketball as well, as the NCAA tournament became more popular than ever.

Dramatic changes in women's basketball occurred in the late 1960s. In 1966 unlimited dribbling became legal, and in 1969 the first five-player full-court game was played. The five-player form became the official game in women's basketball in 1971. Women's basketball is now played with virtually the same rules, regulations, and styles as men's basketball, although the women use a slightly smaller ball at many levels, including college. With the changes of the late 1960s, women's basketball began a period of tremendous growth, and in 1971 the Association for Intercollegiate Athletics for Women (AIAW) was founded, offering a national college basketball tournament for women.

The women's game gained strength in the late 1970s after a law called Title IX was increasingly enforced, helping strengthen women's basketball programs. The law, passed as part of the Education Amendments Act of 1972, prohibited discrimination on the basis of gender in educational institutions receiving federal aid, meaning that women's athletic programs had to be treated as equal to men's programs. In 1978 the AIAW championship was televised, and the same year a professional league called the Women's Basketball League (WBL) made its debut. Featuring eight teams, the league lasted three years. The AIAW disbanded in 1982, but that same year the NCAA held its first national championship for women. Three years later, in 1985, the Basketball Hall of Fame began inducting female coaches, players, and contributors. These inductees include important pioneers such as Ann Meyers, who was the first woman to receive a collegiate athletic scholarship; Carol Blazejowski; Cheryl Miller; Anne Donovan; and Nancy Lieberman-Cline. 

In the 1990s interest in basketball at all levels continued to grow. The most important figure in this growth was guard Michael Jordan, who is considered by many to be the greatest player ever. Jordan's exceptional basketball skills and flair for entertainment helped keep basketball in the forefront of American culture as he led the Chicago Bulls to six NBA championships (1991-1993, 1996-1998) and led the league in scoring a record ten times. Other great players of the 1990s included Hakeem Olajuwon, Scottie Pippen, Charles Barkley, David Robinson, Karl Malone, John Stockton, and Shaquille O'Neal. Star players of the women's professional leagues included Cynthia Cooper, Sheryl Swoopes, Teresa Edwards, Lisa Leslie, and Jennifer Azzi.

Beginning in the late 1980s, it became increasingly common for the best male collegiate players to leave college before graduating, as they chose to enter the NBA draft hoping to play professionally for large sums of money. The NBA, while affording young players this opportunity, has tried to curtail this practice. In 1995 the league enacted a limit on the amount of money a rookie could earn, called a rookie salary cap, hoping to discourage players from leaving school.

Following the 1997-98 season NBA owners and players could not agree on rules regarding a salary cap and several other issues, and the NBA owners instituted a player lockout. The dispute cancelled all league play until an agreement was reached in January 1999, resulting in a strike-shortened, 50-game season followed by a regular playoff schedule and championship series. Jordan announced his retirement from professional basketball after the labor dispute was resolved. The San Antonio Spurs, led by David Robinson and Tim Duncan, won the 1999 NBA title. The Los Angeles Lakers, featuring Shaquille O'Neal and Kobe Bryant, won the 2000 league championship. Duncan and Bryant are part of the next generation of superstars that the league hopes will carry on the legacy of past heroes such as Bird, Johnson, Barkley, and Jordan.