To interfere with the ball while on its downward flight for a basket, or while it is bouncing on the basket, is called goal tending and is a violation. Goal tending is one of the most complicated calls of basketball, and is significantly different in international basketball.

Fouls
An attempt to unfairly disadvantage an opponent with personal contact is illegal and is called a foul. These are most commonly committed by defensive players; however, they can be committed by offensive players as well. Normal fouls are called personal fouls. Players who are fouled either receive the ball to pass inbounds again, or receive a free throw if they are fouled in the act of shooting. One point is awarded for making a free throw, which is attempted from a line 4.5 metres (15 feet) from the basket.

If a team surpasses a preset limit of team fouls in a given period (4 in international and NBA games), the opposing team is awarded free throws on all subsequent fouls for that period. Offensive fouls and double fouls are not counted as team fouls in the NBA, but they are in international games.

A player or coach who shows poor sportsmanship such as arguing with a referee or fighting with another player can be charged with a technical foul. A player or coach with two technical fouls is disqualified from the game and is required to leave the stadium. 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 incur a harsher penalty; in some rare cases a disqualifying foul will require the player to leave the stadium.

If a player commits five fouls (including technical fouls) in one game (six in some professional leagues, including the NBA) he is not allowed to participate for the rest of the game, and is described as having "fouled out". If no substitutes are available, the team must forfeit the game. Some leagues, including the NBA, allow disqualified players to re-enter the game at the cost of a technical foul on the team.

Basketball Players
A team consists of five players and up to seven substitutes, though in series where there are three games or less, only five substitutes are allowed. Any number of player substitutions are allowed during the game, although substitutes can only enter a game during a stoppage of play.

Male players generally wear shorts and a sleeveless top, and high-top sneakers that provide extra ankle support. Female players have worn shirts and skirts in the past, but most female players now wear uniforms identical to those worn by men.

Officials
A referee and one or two umpires control the game, these are the officials. On the scorebench, there are table officials, responsible for the administration of the game. The table officials include the scorer, who keeps track of the score and fouls by each player, the assistant scorer who controls the scoreboard, the timekeeper and the shot clock operator.

Referees and umpires generally wear a grey shirt and black trousers. These officials call fouls, award successful baskets, and so on.