Section 4: Players/Officials
Team Composition
Each NBA team carries a roster of up to 15 players during the regular season, with an additional two-way contract slots (up to 2 players who split time between the NBA team and its G League affiliate). On game day, teams designate 13 active players who are eligible to participate; the remaining players are listed as inactive and may not play (Rule 3).
Player Positions
Each team fields five players on the court at any time. The five traditional positions are:
- Point Guard (PG): The primary ball-handler and playmaker, responsible for running the team's offense, calling plays, and distributing the ball. Typically the best passer and floor general on the team.
- Shooting Guard (SG): Often the team's best perimeter scorer, skilled at shooting from mid-range and three-point distance. Also contributes to ball-handling and defensive assignments on the opposing team's best wing player.
- Small Forward (SF): A versatile position combining scoring, rebounding, and defensive abilities. Small forwards are typically athletic and capable of playing both inside and outside.
- Power Forward (PF): Plays near the basket on offense, contributing scoring in the post and mid-range areas. Responsible for rebounding and interior defense. In the modern NBA, many power forwards also shoot three-pointers (the "stretch four").
- Center (C): Traditionally the tallest player on the team, anchoring the defense near the rim and scoring in the post. Modern centers increasingly operate as rim protectors, screen-setters, and short-roll playmakers.
The modern NBA has embraced positionless basketball, with many players capable of filling multiple roles. Teams frequently use lineups that do not conform to traditional position designations (Rule 3).
Substitutions
- Substitutions may be made during any dead ball situation (after a made basket, during a timeout, after a foul, after a violation, or at the start of a period) (Rule 3)
- A substitute must report to the scorer's table and wait to be beckoned onto the court by an official (Rule 3)
- There is no limit to the number of substitutions a team may make during a game (Rule 3)
- A player who has fouled out (6 personal fouls) must be replaced immediately and may not re-enter the game (Rule 3)
- If a team is reduced to fewer than 5 eligible players due to fouls, injuries, or ejections, the last player to have fouled out is allowed to remain in the game and is charged a technical foul for each subsequent personal foul (Rule 3)
Game Officials (3 Referees)
Each NBA game is officiated by a crew of three referees:
- Crew Chief: The senior official with final authority on all rule interpretations and disputes. Administers the game and has sole authority to forfeit a game (Rule 2).
- Referee: The second official, sharing floor responsibilities with the crew chief. Assists in all calls and reviews (Rule 2).
- Umpire: The third official. All three referees rotate positions throughout the game (lead, trail, and slot/center) to ensure comprehensive court coverage (Rule 2).
Official Positioning
- Lead official: Positioned along the baseline near the basket, responsible for play around the rim, post defense, and out-of-bounds calls along the baseline (Rule 2)
- Trail official: Positioned near the half-court line on the ball-side, monitoring perimeter play, three-point shooting, and backcourt activity (Rule 2)
- Slot (center) official: Positioned on the opposite side of the court from the trail official, covering weak-side action and off-ball fouls (Rule 2)
Additional Game Personnel
- Scorer: Maintains the official score, records all field goals, free throws, fouls, and timeouts (Rule 2)
- Timer: Operates the game clock, starting and stopping it as directed by the officials (Rule 2)
- Shot clock operator: Operates the 24-second shot clock, resetting it as required by the rules (Rule 2)
- Replay Center: Located in Secaucus, New Jersey, the NBA Replay Center staffs officials who review plays via video to assist the on-court crew with specific reviewable matters (Rule 2)
- Alternate official: A fourth referee is present at all games to replace any on-court official who becomes unable to continue (Rule 2)