The Women's National Basketball Association (WNBA) is a professional women's basketball league based in the United States with 12 teams as of 2024. The league was founded in 1996 by the men's National Basketball Association (NBA) as a wholly-owned subsidiary and began play in the 1997 season with eight teams. WNBA shares the same court dimensions, hoop height, and shot clock length as NBA, but has had shorter quarters of ten minutes each since 2006 and uses a smaller ball to match with international FIBA standards. Full NBA ownership of the league ended in 2002 and new independent ownership groups began investing in franchises; the WNBA has seven teams with independent ownership and five that are under the same ownership as an NBA team and share the same home arena.

The league's 12 teams are organized into the Eastern and Western conferences; a 13th team is scheduled to begin play in the 2025 season. The number of WNBA teams has varied since the league's original eight in 1997 due to expansions and later contractions; the first expansion teams were added in 1998 and were followed by two more rounds of additions that brought the total to 16 teams in 2000. Following the change in NBA ownership in 2002, the WNBA lost two teams. The league lost two more teams by 2006 but expanded to remain at 13 teams. The number of teams has remained at 12 since the Houston Comets ceased operations after the 2008 season.

As of the 28th season in 2024, each team plays 40 games during the regular season, which runs from May to September. The 2024 season includes a month-long break for the Summer Olympic Games that begins after the annual WNBA All-Star Game in mid-July. The summer schedule is mostly played during the NBA offseason, which allows teams to share venues; during the WNBA offseason, many players transfer to overseas leagues that follow a fall and winter schedule. Teams play four games against opponents in the same conference and two teams from the other conference; three games are played against the remaining four teams in the other conference. Five regular season games in early June are played against teams in the same conference to determine qualification for the WNBA Commissioner's Cup, an in-season tournament first played in 2021; the final is hosted by the team with the better win–loss record in qualifying games.

The eight teams with the best regular season records, regardless of conference, qualify for the WNBA playoffs to determine the league's champion in the WNBA Finals. Since 2022, the playoffs have used a best-of-three series in the first round, where teams are seeded based on regular season performance, and a best-of-five format for the semifinals and WNBA Finals. The most successful playoff teams are the Minnesota Lynx, Seattle Storm, and defunct Houston Comets, who have each won four WNBA championships; the Lynx have made six appearances in the WNBA Finals, the most in league history. Three current WNBA teams have yet to win a championship; among them, the Connecticut Sun has finished as runners-up in four WNBA Finals.

The best regular season performance in league history was set in the 1998 season by the Houston Comets, who finished with a 27–3 win–loss record—a winning percentage of 0.900. The number of games played by WNBA teams has steadily increased since the initial 28-game schedule in the inaugural season; for most of the league's history, teams played 34 games before the schedule was expanded to 36 games in 2022 and 40 games in 2023. The Las Vegas Aces won 34 games during the expanded 2023 season and set a record for most wins in a WNBA season. The WNBA playoffs has also changed its format several times; until 2016, the two conferences were separated until the WNBA Finals. Under the cross-conference format, top-seeded teams received single or double byes and some rounds had single-elimination games instead of a best-of-five series. The format was simplified in 2022 to remove single-elimination rounds and byes.

WNBA seasons

Season	Teams	Playoffs			Regular season			Commissioner's Cup winner	Ref.
		Champion	Series	Runners-up	Top seed	Record	Games
1997	8	Houston Comets	1–0	New York Liberty	Houston Comets	18–10	28	Not established until 2020
1998	10	Houston Comets (2nd title)	2–1	Phoenix Mercury	Houston Comets	27–3	30
1999	12	Houston Comets (3rd title)	2–1	New York Liberty	Houston Comets	26–6	32
2000	16	Houston Comets (4th title)	2–0	New York Liberty	Los Angeles Sparks	28–4	32
2001	16	Los Angeles Sparks	2–0	Charlotte Sting	Los Angeles Sparks	28–4	32
2002	16	Los Angeles Sparks (2nd title)	2–1	New York Liberty	Los Angeles Sparks	25–7	32
2003	14	Detroit Shock	2–1	Los Angeles Sparks	Detroit Shock	25–9	34
2004	13	Seattle Storm	2–1	Connecticut Sun	Los Angeles Sparks	25–9	34
2005	13	Sacramento Monarchs	3–1	Connecticut Sun	Connecticut Sun	26–8	34
2006	14	Detroit Shock (2nd title)	3–2	Sacramento Monarchs	Connecticut Sun	26–8	34
2007	13	Phoenix Mercury	3–2	Detroit Shock	Detroit Shock	24–10	34
2008	14	Detroit Shock (3rd title)	3–0	San Antonio Silver Stars	San Antonio Silver Stars	24–10	34
2009	13	Phoenix Mercury (2nd title)	3–2	Indiana Fever	Phoenix Mercury	23–11	34
2010	12	Seattle Storm (2nd title)	3–0	Atlanta Dream	Seattle Storm	28–6	34
2011	12	Minnesota Lynx	3–0	Atlanta Dream	Minnesota Lynx	27–7	34
2012	12	Indiana Fever	3–1	Minnesota Lynx	Minnesota Lynx	27–7	34
2013	12	Minnesota Lynx (2nd title)	3–0	Atlanta Dream	Minnesota Lynx	26–8	34
2014	12	Phoenix Mercury (3rd title)	3–0	Chicago Sky	Phoenix Mercury	29–5	34
2015	12	Minnesota Lynx (3rd title)	3–2	Indiana Fever	New York Liberty	23–11	34
2016	12	Los Angeles Sparks (3rd title)	3–2	Minnesota Lynx	Minnesota Lynx	28–6	34
2017	12	Minnesota Lynx (4th title)	3–2	Los Angeles Sparks	Minnesota Lynx	27–7	34
2018	12	Seattle Storm (3rd title)	3–0	Washington Mystics	Seattle Storm	26–8	34
2019	12	Washington Mystics	3–2	Connecticut Sun	Washington Mystics	26–8	34
2020	12	Seattle Storm (4th title)	3–0	Las Vegas Aces	Las Vegas Aces	18–4	†22	Not held
2021	12	Chicago Sky	3–1	Phoenix Mercury	Connecticut Sun	26–6	32	Seattle Storm
2022	12	Las Vegas Aces	3–1	Connecticut Sun	Las Vegas Aces	26–10	36	Las Vegas Aces
2023	12	Las Vegas Aces (2nd title)	3–1	New York Liberty	Las Vegas Aces	34–6	40	New York Liberty
2024	12	New York Liberty	3–2	Minnesota Lynx	New York Liberty	32–8	40	Minnesota Lynx

• WNBA website