The UEFA Champions League is referred to as simply the Champions League and is the biggest club competition in Europe and, probably, the biggest in the world. The Champions League takes the champions of each of the UEFA (Union of European Football Associations) leagues with the bigger leagues having more entries, and pits them against each other in a tournament that runs from July until May.
The Champions League begins with three knockout stage playoff rounds and then the 10 clubs that survive that advance to the 32-team group stage, where 22 clubs automatically qualify. There are eight groups of four clubs that each play a home-and-away leg against the three other clubs in the group. The top two clubs advance to the knockout stage where there is another home-and away leg to determine who advances to the next round. This culminates in a winner-take-all one-match final.
The winner of the Champions League qualifies for the UEFA Super Cup and the FIFA Club World Cup. There were European club competitions that began in 1955, and the current Champions League format was established in 1992. In the 2013 final when Bayern Munich beat Borussia Dortmund 2-1 the match was the most watched sporting event worldwide of the year.
The Champions League has been won by 22 clubs, with 12 that have won at least twice. Real Madrid has been the dominant club in the competition with 10 titles. The top four clubs from the bigger leagues of Europe in Spain, England, and Germany each receive four automatic Champions League entries, with Italy having three.