In basketball, each team has five players on the court at one time. Player substitutions are unlimited but must be made during a dead ball stoppage and be recognized by one of the game officials (called a referee).
Basketball is played on a court that has two basketball hoops (the net is 10 feet off the floor, but for younger kids (K-2) may be 8 feet off the floor) on each end. The court is separated into an offensive and defensive zone by the mid-court line. The offensive team (the team that has the ball) has ten seconds to advance the ball to the mid-court line (half court); if it doesn't, possession of the ball is turned over to the other team.
A player can move the ball around the court by passing to another teammate or dribbling. The team on defense tries to regain possession by stealing the ball, intercepting passes, and rebounding missed shots. Many youth basketball programs prohibit the defense from stealing the ball from the player handling the ball and allow steals only on a pass.
Each team has a basket to defend, and at halftime, the teams switch baskets. The game begins with two players (one from each team) at center court where a referee tosses the ball between the two (the "tip-off" or a "jump ball").
Each game is divided into halves and sometimes into quarters, depending on the level of play:
Pros: four 12 minute quarters. No running clock.
College: two 20-minute halves. No running clock.
Middle and high school: four 8- minute quarters. No running clock.
Youth level: two 20-minute halves, often with a running clock (the clock stopping only for dead balls in the last minute of each half)