Section 1: Introduction
The National Basketball Association (NBA) is the premier professional basketball league in the world, featuring 30 teams divided into two conferences — the Eastern Conference and the Western Conference — each comprising three divisions of five teams. The NBA is widely regarded as the highest level of professional basketball competition globally.
Basketball was invented in December 1891 by Dr. James Naismith, a Canadian-American physical education instructor at the International YMCA Training School in Springfield, Massachusetts. The NBA itself was founded on June 6, 1946, as the Basketball Association of America (BAA) in New York City. It adopted the name National Basketball Association in 1949 after merging with the rival National Basketball League (NBL).
The league is governed by a Commissioner, currently Adam Silver, who has served since February 2014. The NBA's rules are maintained by the NBA Competition Committee, which reviews and proposes rule changes annually. Changes are voted on by the league's Board of Governors, typically during the offseason.
Each team plays an 82-game regular season schedule spanning from October through April. The top teams from each conference qualify for the NBA Playoffs, a best-of-seven elimination tournament that culminates in the NBA Finals. The NBA also operates a developmental league, the NBA G League, a summer league program, and the NBA Draft to replenish team rosters.
The NBA has a rich history of legendary players, including Bill Russell, Wilt Chamberlain, Kareem Abdul-Jabbar, Magic Johnson, Larry Bird, Michael Jordan, Kobe Bryant, LeBron James, and Stephen Curry. The league has expanded from its original 11 teams to 30 franchises across the United States and Canada (the Toronto Raptors).
Section 2: Equipment
The Basketball
The official NBA game ball is manufactured by Wilson (replacing Spalding beginning with the 2021-2022 season). It must meet the following specifications:
- Size: Size 7 (men's official) with a circumference of 29.5 inches (74.9 cm)
- Weight: 22 ounces (623.7 g)
- Material: Full-grain Horween leather with a pebbled surface for consistent grip
- Inflation: Between 7.5 and 8.5 pounds per square inch (psi)
- Bounce: When dropped from a height of 6 feet (1.83 m) onto a hardwood floor, the ball must bounce to a height of 49 to 54 inches (124.5–137.2 cm)
- Color: Traditional orange with black seams and the NBA logo
Each team is required to have a minimum of three game balls available for each game. Home teams supply the game balls, which must be approved by the game officials prior to tip-off.
Backboard and Rim
- Backboard: Rectangular, 6 feet (1.83 m) wide by 3.5 feet (1.07 m) tall, made of transparent tempered glass or polycarbonate with a 2-inch (5.08 cm) white border
- Rim (basket): 18 inches (45.7 cm) in internal diameter, made of 5/8-inch (1.59 cm) diameter steel rod, painted orange
- Rim height: 10 feet (3.05 m) above the playing floor, measured to the top edge of the rim
- Net: White cord, 15 to 18 inches (38.1–45.7 cm) in length, designed to momentarily check the ball as it passes through the basket
- Breakaway rim: All NBA baskets use breakaway (spring-loaded) rims designed to flex downward under pressure and return to horizontal, preventing backboard damage and reducing injury risk during dunks
Player Uniforms
- Jersey: Each player must wear a jersey with a unique number (0–99) on both the front and back. Numbers must be at least 6 inches (15.2 cm) tall on the back and 4 inches (10.2 cm) on the front.
- Shorts: Must be of a uniform color matching the team's designated uniform for that game
- Shoes: Basketball shoes must be worn; no open-toed or non-athletic footwear is permitted. The NBA has relaxed color restrictions, allowing players to wear shoes of any color.
- Compression gear: Undershirts, tights, and arm/leg sleeves are permitted but must match the predominant color of the jersey
- Headbands and wristbands: Permitted in team-approved colors; headbands must be no wider than 2 inches
Prohibited Equipment
- Jewelry of any kind (rings, necklaces, earrings, watches) during games
- Hard or dangerous objects that could cause injury (casts, splints, or braces must be padded and approved by the officials)
- Unapproved commercial logos or personal messaging on uniforms or equipment
- Sticky substances on hands or the ball
Shot Clock and Game Clock
- Shot clock: Visible displays mounted above each backboard, showing the 24-second shot clock countdown. Must be visible to players, officials, and spectators.
- Game clock: Centrally located scoreboard displaying game time, score, period, team fouls, and timeouts remaining
- LED lights: Backboard-mounted LED strips that illuminate red when the shot clock or game clock expires, providing visual confirmation for officials
Section 3: Playing Area
The Court
The NBA playing court is a rectangular, flat, hard surface with the following dimensions:
- Length: 94 feet (28.65 m)
- Width: 50 feet (15.24 m)
- Surface: Hardwood (typically maple), sanded and finished to provide consistent ball bounce and player traction. All NBA courts are indoor facilities with climate-controlled environments.
Court Markings
All court boundary lines and markings are 2 inches (5.08 cm) wide and painted in a contrasting color to the floor surface. Key markings include:
- Sidelines: The two longer boundary lines running the length of the court (94 feet)
- Baselines (end lines): The two shorter boundary lines running the width of the court (50 feet), located behind each basket
- Half-court line: A line dividing the court into two equal halves at the 47-foot mark, extending the full width of the court
- Center circle: A circle with a radius of 6 feet (1.83 m) at the center of the court, used for the opening tip-off
The Key (Painted Area / Lane)
The key, also known as the paint, free throw lane, or restricted area, is the rectangular region beneath each basket:
- Width: 16 feet (4.88 m) — the NBA widened the lane from 12 feet to 16 feet in 1951 to reduce dominant post play
- Length: 19 feet (5.79 m) from the baseline to the free throw line
- Free throw line: 15 feet (4.57 m) from the face of the backboard and 19 feet from the baseline
- Free throw circle: A circle with a radius of 6 feet (1.83 m) centered on the free throw line
- Lane space marks: Marked along each side of the lane to position players during free throw attempts. The first mark is 7 feet from the baseline, and subsequent marks are 12 inches apart. Two offensive players and three defensive players occupy these spaces (excluding the shooter).
Three-Point Line
The NBA three-point line is an arc surrounding each basket:
- Arc distance: 23 feet 9 inches (7.24 m) from the center of the basket at the apex
- Corner distance: 22 feet (6.71 m) from the center of the basket in the corners, where the arc meets the sideline. The line runs parallel to the sideline for a short distance at each corner.
- History: The NBA adopted the three-point line for the 1979-1980 season. It was briefly shortened to a uniform 22 feet from 1994 to 1997 before being restored to its current dimensions.
Restricted Area Arc
- Location: A semicircular arc painted on the floor directly beneath the basket with a radius of 4 feet (1.22 m) from the center of the basket
- Purpose: A defensive player standing within the restricted area arc cannot draw an offensive charging foul, except in specific circumstances (e.g., a secondary defender moving laterally to establish legal guarding position before the offensive player gathers the ball)
Team Bench Areas
Each team's bench area is located on the same side of the court as the scorer's table. The first seat must be a minimum of 28 feet from the nearest baseline. Only players listed on the active roster, coaches, trainers, and authorized team personnel may occupy the bench area during the game.
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.
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.
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)
- A substitute must report to the scorer's table and wait to be beckoned onto the court by an official
- There is no limit to the number of substitutions a team may make during a game
- A player who has fouled out (6 personal fouls) must be replaced immediately and may not re-enter the game
- 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
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.
- Referee: The second official, sharing floor responsibilities with the crew chief. Assists in all calls and reviews.
- Umpire: The third official. All three referees rotate positions throughout the game (lead, trail, and slot/center) to ensure comprehensive court coverage.
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
- Trail official: Positioned near the half-court line on the ball-side, monitoring perimeter play, three-point shooting, and backcourt activity
- Slot (center) official: Positioned on the opposite side of the court from the trail official, covering weak-side action and off-ball fouls
Additional Game Personnel
- Scorer: Maintains the official score, records all field goals, free throws, fouls, and timeouts
- Timer: Operates the game clock, starting and stopping it as directed by the officials
- Shot clock operator: Operates the 24-second shot clock, resetting it as required by the rules
- 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
- Alternate official: A fourth referee is present at all games to replace any on-court official who becomes unable to continue
Section 5: Rules of Play
Game Duration
An NBA game consists of four 12-minute quarters, for a total of 48 minutes of regulation play. The game clock stops for dead balls, fouls, violations, timeouts, and other stoppages, meaning actual elapsed time is significantly longer (typically 2 to 2.5 hours).
- Halftime: A 15-minute intermission occurs between the second and third quarters (extended for nationally televised and playoff games)
- Between quarters: A 130-second break occurs between the first and second quarters and between the third and fourth quarters
- Two-minute warning: The officials notify both teams when 2 minutes remain in the fourth quarter and in any overtime period
Shot Clock (24 Seconds)
The offensive team must attempt a shot that hits the rim within 24 seconds of gaining possession of the ball. The shot clock was introduced in the 1954-1955 season to increase pace of play and scoring.
- Full reset (24 seconds): After a change of possession, after the ball goes out of bounds off the defensive team, or after a kicked ball or punched ball violation by the defense
- Partial reset (14 seconds): After an offensive rebound, after the ball goes out of bounds off the offensive team and is retained (in the frontcourt), after a kicked ball or punched ball violation by the defense in the frontcourt, after a loose ball foul committed by the defensive team, or after a jump ball situation where the offensive team retains possession
- Shot clock violation: If the shot clock expires before a valid shot attempt (one that hits the rim), the opposing team is awarded possession. The ball is inbounded from the sideline nearest to where the violation occurred.
Starting Play
- Jump ball: Each game and overtime period begins with a jump ball at center court. Two opposing players stand inside the center circle, and the referee tosses the ball upward between them. Each jumper may tap the ball after it reaches its highest point.
- Alternating possession: After the opening jump ball, all subsequent jump ball situations (held balls, simultaneous possession) are resolved using the alternating possession arrow. The team that did not gain initial possession from the opening tip receives the next alternating possession.
Ball Advancement (Backcourt / Frontcourt)
- The offensive team must advance the ball past the half-court line within 10 seconds of gaining possession in the backcourt (8-second rule in FIBA; NBA uses 10 seconds as of the current rules)
- Once the ball has been established in the frontcourt (both feet of the ball-handler and the ball are past the half-court line), the offensive team may not return the ball to the backcourt — doing so is a backcourt violation (over-and-back)
Timeouts
- Each team is granted 7 timeouts per game (no distinction between full and 20-second timeouts since the 2017-2018 season)
- Each timeout is 75 seconds in duration
- Teams are limited to 4 timeouts in the fourth quarter and may not carry more than 2 timeouts into the final 3 minutes of the fourth quarter (excess timeouts are forfeited)
- Each team receives 2 timeouts per overtime period (unused regulation timeouts do not carry over)
- Mandatory timeouts: One timeout must be taken by each team in each quarter. If no team has called a timeout by the 6:59 mark of each quarter, a mandatory timeout is charged to the home team; a second mandatory timeout occurs at the 2:59 mark if needed.
Overtime
- If the score is tied at the end of the fourth quarter, a 5-minute overtime period is played
- Overtime begins with a jump ball at center court
- Each team receives 2 timeouts per overtime period
- Additional overtime periods are played until one team has a higher score at the end of a period — NBA games cannot end in a tie
- Personal fouls carry over from regulation into overtime; team foul counts reset to zero for each overtime period
Inbounding the Ball
- After a made field goal or free throw (in non-dead-ball situations), the opposing team inbounds from behind the baseline anywhere. No timeout is needed and the 5-second inbound count begins immediately.
- After a violation, a foul resulting in a throw-in, or an out-of-bounds play, the ball is inbounded from the designated spot nearest to the infraction. The inbounding player has 5 seconds to release the pass.
- In the final 2 minutes of the fourth quarter and overtime, a team calling a timeout after a made basket may elect to inbound from the frontcourt sideline (at the 28-foot mark) instead of behind the baseline.
Section 6: Scoring
Field Goals
- Two-point field goal (2 points): A basket made from inside the three-point arc (within 23 feet 9 inches of the basket, or 22 feet in the corners). This includes layups, dunks, hook shots, floaters, and mid-range jump shots.
- Three-point field goal (3 points): A basket made from beyond the three-point arc. The shooter's feet must be completely behind (not touching) the three-point line at the time of the shot. If any part of the shooter's foot is on the line, the basket counts as two points.
Free Throws
- Free throw (1 point each): Uncontested shots taken from the free throw line (15 feet from the backboard), awarded after certain fouls
- The shooter must release the ball within 10 seconds of receiving it from the official
- Other players line up in designated lane spaces during free throw attempts: two offensive players occupy the first spaces closest to the baseline, and three defensive players occupy the second and third spaces on each side
- Players may not enter the lane or cross the free throw line extended until the ball touches the rim
- If the free throw attempt is the last of a set and is successful, the opposing team inbounds from behind the baseline
- If the free throw attempt is the last of a set and is missed, the ball is live and may be rebounded by either team
Free Throw Situations
- Shooting foul (non-three-point): The fouled player receives 2 free throws
- Shooting foul (three-point attempt): The fouled player receives 3 free throws
- Shooting foul with made basket (and-one): The basket counts, and the fouled player receives 1 additional free throw
- Non-shooting foul (team in penalty): The fouled player receives 2 free throws when the opposing team has committed 5 or more fouls in the current quarter (team is "in the bonus")
- Technical foul: 1 free throw awarded, followed by possession for the offended team at the sideline
- Flagrant foul 1: 2 free throws plus possession for the offended team
- Flagrant foul 2: 2 free throws plus possession for the offended team; the offending player is ejected
Determining the Scorer
The player who last controls the ball on a successful shot attempt is credited with the field goal or free throw. If a player tips in a teammate's missed shot, the tipping player is credited with the basket. Own goals (accidentally scoring in the opponent's basket) are credited to the nearest opposing player.
Standings and Tiebreakers
NBA teams are ranked by win-loss percentage. In the event of a tie, the following tiebreakers are applied in order: head-to-head record, division record (if applicable), conference record, record against playoff teams in the same conference, record against playoff teams in the opposing conference, net point differential, and finally a coin flip.
Playoff Format
The NBA Playoffs feature 16 teams (8 per conference). The top 6 seeds in each conference qualify directly. Teams seeded 7th through 10th compete in the Play-In Tournament: 7 vs. 8 (winner earns 7th seed), 9 vs. 10 (loser eliminated), and the loser of 7-vs-8 plays the winner of 9-vs-10 for the 8th seed. Playoff series are best-of-seven in every round, culminating in the NBA Finals.
Section 7: Violations/Penalties
Personal Fouls
A personal foul is illegal physical contact by a player against an opponent. Personal fouls include holding, pushing, charging, blocking, hand-checking, and illegal screens. Each player is allowed a maximum of 6 personal fouls per game; upon committing a sixth foul, the player is disqualified ("fouled out") and must leave the game.
Team Fouls and the Bonus
- Each team's personal fouls are tracked per quarter. When a team commits 5 or more fouls in a quarter, the opposing team enters the "bonus" (also called the penalty).
- While in the bonus, all subsequent non-offensive defensive fouls result in 2 free throws for the fouled player, regardless of whether the foul occurred during a shot attempt.
- Team fouls reset to zero at the start of each quarter. In overtime, the team foul count resets for each overtime period.
Flagrant Fouls
- Flagrant Foul 1 (unnecessary contact): Contact that is unnecessary but not excessive. Penalty: 2 free throws and possession for the offended team. The play is reviewable by officials and the Replay Center.
- Flagrant Foul 2 (unnecessary and excessive contact): Contact that is both unnecessary and excessive. Penalty: 2 free throws, possession for the offended team, and immediate ejection of the offending player. The player may face additional fines and suspension from the league office.
- Flagrant foul points accumulate throughout the season. A player who accumulates a specified number of flagrant foul points is subject to automatic suspension.
Technical Fouls
- Unsportsmanlike conduct: Taunting, excessive arguing with officials, using profanity, or engaging in actions that disrespect the game
- Delay of game: Interfering with the ball after a made basket, failing to immediately pass the ball to the nearest official after a violation
- Illegal defense: Historically penalized (pre-2001 zone defense ban), this is no longer a violation in the current NBA rules
- Hanging on the rim: A player may not hang on the rim unless doing so is necessary to avoid injury to themselves or another player
- Penalty: 1 free throw plus possession for the offended team. A player who receives 2 technical fouls in a game is automatically ejected. A player who accumulates 16 technical fouls during the regular season receives an automatic one-game suspension, with additional suspensions for every subsequent two technicals.
Ball-Handling Violations
- Traveling: Moving one's pivot foot or taking more than two steps without dribbling the ball. The NBA allows a "gather step" — once a player gathers the ball (picks up the dribble or catches a pass), they may take two additional steps before stopping, passing, or shooting.
- Double dribble: Dribbling the ball, stopping, and then dribbling again. Also called for dribbling with both hands simultaneously.
- Carrying (palming): Allowing the ball to rest momentarily in the palm or turning the hand over (under the ball) while dribbling, gaining an illegal advantage in ball control.
- Kicked ball: Intentionally striking the ball with any part of the leg or foot. Accidental contact with the foot is not a violation.
Timing Violations
- Shot clock violation (24 seconds): Failure to attempt a shot that hits the rim within 24 seconds of gaining possession
- Backcourt violation (10 seconds): Failure to advance the ball past the half-court line within 10 seconds of gaining possession in the backcourt
- 5-second inbound violation: Failure to pass the ball inbounds within 5 seconds
- 5-second closely guarded violation: Holding the ball for 5 seconds while being closely guarded (within 6 feet) without dribbling, passing, or shooting (note: this rule applies only to holding, not to dribbling in the NBA)
Lane Violations
- Offensive three-second violation: An offensive player may not remain in the paint (the key / free throw lane) for more than 3 consecutive seconds while their team has possession of the ball in the frontcourt. The count resets when the player exits the lane, a shot is attempted, or there is a loss of team control.
- Defensive three-second violation: A defensive player may not remain in the paint for more than 3 consecutive seconds unless they are actively guarding an offensive player within arm's reach. Penalty: a technical foul assessed to the offending team (1 free throw to the opposing team). This rule was introduced in the 2001-2002 season to open up driving lanes.
Goaltending and Basket Interference
- Defensive goaltending: A defender may not touch the ball while it is on its downward arc toward the basket, above the rim level, or after it has touched the backboard. If a defensive goaltending violation occurs, the basket counts automatically.
- Offensive goaltending / basket interference: An offensive player may not touch the ball while it is on or within the cylinder above the rim, or touch the rim or net while the ball is on or within the basket. If an offensive violation occurs, the basket is disallowed.
Other Violations
- Out of bounds: The ball is out of bounds when it touches the floor, a player, or any object on or outside the boundary line. Possession is awarded to the opposing team of the player who last touched the ball.
- Backcourt violation (over and back): Once the ball is established in the frontcourt, the offensive team may not cause the ball to return to the backcourt. Penalty: turnover.
- Illegal screen (moving pick): An offensive player setting a screen must be stationary; if they are moving or leaning into the defender when contact occurs, a foul is called on the screener.
Section 8: Safety Considerations
Concussion Protocol
The NBA maintains a comprehensive concussion management program developed in collaboration with the National Basketball Players Association (NBPA). The protocol includes the following key elements:
- Baseline testing: All players undergo baseline neurocognitive testing (ImPACT or equivalent) during the preseason. These results serve as a reference point if a concussion is suspected during the season.
- In-game evaluation: If a player exhibits signs of a concussion (loss of consciousness, disorientation, balance problems, blank stare, slow response), they are immediately removed from the game for evaluation by the team physician.
- No same-day return: A player diagnosed with a concussion may not return to play in the same game.
- Return-to-play protocol: The player must complete a graduated, multi-step return-to-participation process supervised by the team physician and reviewed by an independent concussion specialist before being cleared to play.
- Independent physicians: The NBA employs independent concussion consultants who may flag players for evaluation and must approve the return-to-play clearance.
NBA Replay Center
The NBA Replay Center, located in Secaucus, New Jersey, serves as a centralized hub for instant replay review. Staffed by league officials, the Replay Center assists on-court referees with specific reviewable matters, including:
- Whether a shot was a two-pointer or a three-pointer (shooter's foot on the line)
- Whether a shot was released before the shot clock or game clock expired
- Flagrant foul review (determining if contact was unnecessary, excessive, or both)
- Out-of-bounds plays in the last 2 minutes of the fourth quarter and overtime
- Goaltending and basket interference calls
- Clock malfunctions and correct time determinations
- Coach's challenge reviews (each team receives one challenge per game to contest certain calls)
Coach's Challenge
Each team is entitled to one Coach's Challenge per game. A coach may challenge a personal foul called on their team, a goaltending or basket interference call, or an out-of-bounds call. To initiate a challenge, the team must have at least one timeout remaining. If the challenge is successful (the call is overturned), the team retains its timeout. If unsuccessful, the team is charged a timeout.
Flagrant Foul Review and Player Ejection
- Officials are required to review all contact that may warrant a flagrant foul assessment, either in real time or via triggered Replay Center review
- A Flagrant Foul 2 results in automatic ejection; the player must leave the court and the arena vicinity
- Two technical fouls on the same player result in automatic ejection
- The league office reviews all ejections, flagrant fouls, and altercations after the game and may impose additional discipline including fines and suspensions
Player Safety on the Court
- Stanchion padding: The basket support stanchion (pole) is padded to reduce injury risk from player collisions
- Courtside seating: The NBA requires a minimum distance between the court boundary and the first row of spectator seating (typically 3 to 4 feet) to provide a buffer zone for players diving for loose balls
- Wet spot protocol: Teams employ dedicated mop crews to immediately dry any wet spots on the court caused by condensation, spills, or perspiration to prevent slipping injuries
- Camera and equipment placement: Courtside cameras, media personnel, and equipment must be positioned to minimize collision risk with players moving at high speed
Anti-Fighting Rules
- Any player who leaves the bench area during an altercation on the court is subject to automatic suspension and fine, even if they do not participate in the altercation
- Players involved in fighting are subject to ejection, fines (minimum $50,000), and suspension (minimum one game)
- The "Malice at the Palace" incident (2004) led to significantly strengthened anti-fighting penalties and protocols for crowd interactions
Health and Safety Protocols
- Arena temperature: NBA arenas must maintain a playing floor temperature between 65 and 75 degrees Fahrenheit for player comfort and safety
- Medical staff: Each team must have a certified athletic trainer and team physician present at all games and practices
- Cardiac screening: All players undergo comprehensive cardiovascular screening, including echocardiograms, as part of their annual physical examination
- Mental health: The NBA and NBPA provide confidential mental health and wellness resources to all players, including licensed psychologists and counselors
- Drug testing: The NBA maintains an anti-drug program that includes random testing for performance-enhancing drugs, drugs of abuse, and diuretics/masking agents during the season and offseason
