Basketball, popular indoor team sport in the United States, the object of which is to score points by propelling a leather ball through a basket (hoop and net). Two baskets, 18 in (46 cm) in diameter and 10 ft (3 m) from the floor, are fixed on two backboards situated at either end of a court, the maximum dimensions of which are 94 × 50 ft (29 × 15 m). Basketball is played between 2 teams, each of 12 players and a coach, with 5 players from each team allowed on court at any one time (2 forwards, 2 guards, and a center, who is usually the tallest player on the team). The coach calls timeouts, advising the team on tactics and substituting players on the “bench” for players who are tired, injured, off their stride, or disqualified. The ball is moved by passing from one player to another or by an individual player dribbling (bouncing) it, never by kicking or by carrying it more than one and a half steps. In addition to game violations involving illegal moves with the ball, there are personal fouls, involving bodily contact or unsportsmanlike conduct. Five fouls disqualify a player from the game. Basketball is a fast-moving game played within a relatively confined space. The game is split into 2 or 4 equal periods of play, with the actual playing time for the whole game varying between 32 minutes and one hour depending upon the level and whether U.S. or international rules govern the game. The World Congress of the International Federation of Basketball approved several modifications to the rules of the game as of the 1984–85 season, including a 3-point basket for distance shots.
Originated by Dr. James A. Naismith in 1891, the game caught on rapidly, and in 1894 the YMCA collaborated with the Amateur Athletic Union in administering the new sport. In 1898 teams from New York, Brooklyn, Philadelphia, and Southern New Jersey formed the first professional league. International interest in basketball was first kindled by an exhibition game played at the 1904 Olympic Games in St. Louis, Missouri. The rules had been translated into 30 languages by 1913, when it was estimated that as many as 20 million people were playing the game throughout the world. The universities of Pennsylvania and Yale were the first to play college basketball, and in 1908 the National Collegiate Athletic Association was formed, establishing rules governing play in both colleges and secondary schools. The game was once dominated by New York's Celtics (1915–28), the all-black New York Renaissance (1923–40s), and the all-black Harlem Globetrotters (formed 1928). Like the original New York Celtics, the Globetrotters became an exhibition team.
Top-level college basketball was first brought to large audiences when Ned Irish, a sportswriter, convinced the promoters of athletic events at Madison Square Garden in New York that basketball could draw large crowds in a metropolitan sports arena. The National Collegiate Athletic Association championships began in 1939. A Stanford player, Hank Luisetti, demonstrated his jump shot to Eastern players during the late 1930s, and adoption of this shot caused the game to become much faster, with scores rocketing to the 70s and 80s. Despite many new rules designed to arrest this trend, scores have continued to rise as players become both taller and more proficient. The fast break and the technique of screening (blocking) to set up plays, backed up by tall centers to take the rebounds and other offensive tactics, have been countered by the use of player-to-player and zone defense. In 1949, the professional National Basketball League (formed in 1937) merged with the Basketball Association of America (organized in 1946). However, it was not until the 1970s that the NBA, expanded and after a merger with the new American Basketball Association (1967), became the solid crowd-drawing equivalent of professional leagues in other sports. Basketball is played in more countries than any other team ball game, and remains among the most popular player/spectator sports in the United States.