The Fußball-Bundesliga (commonly the Bundesliga, Federal League) is a professional association football league in Germany. At the top of the German football league system, it is Germany's primary football competition. The Bundesliga is contested by 18 teams and operates on a system of promotion and relegation with the 2. Bundesliga. Seasons run from August to May. Most games are played on Saturdays and Sundays, with a few games played during weekday evenings.
A total of 51 clubs have competed in the Bundesliga since its founding. FC Bayern Munich has won the Bundesliga the most, winning the title 21 times. However, the Bundesliga has seen other champions with Borussia Dortmund, Hamburger SV, Werder Bremen, Borussia Mönchengladbach and VfB Stuttgart most prominent among them. The Bundesliga is one of the top national leagues, currently ranked 3rd in Europe according to UEFA's league coefficient ranking, based on recent European performances. The Bundesliga is the number one football league in the world in terms of average attendance; out of all sports, its average of 45,134 fans per game during the 2011–12 season was the second highest of any sports league in the world.
Unlike other countries, in Germany a unified national football league structure was quite late in developing. The Bundesliga was not formed until 1963 and the structure and organisation of the nation's football leagues have undergone frequent changes right up to the present day. The league was originally founded by the German Football Association, but is now operated by the Deutsche Fußball Liga.