No other club competition in world football can match the popularity and appeal of the UEFA Champions League (UCL). The best teams from all the European leagues compete in this tournament, competing for the coveted trophy and the title known every year as "Europe's best". While other continental federations such as the Asian Football Confederation, the African Football Confederation and the South American Football Confederation (CONMEBOL) also host their own continental Champions League, European football's overwhelming popularity around the world has made UCL stand out as a competition.
Organised by the European Football Governing Body (UEFA), the inaugural UCL was held in 1955 and was not known as the European Cup until 1992. In the early days UCL was a knockout tournament in which champions from different domestic leagues in Europe participated. The round-robin or group stage was introduced in 1991, allowing multiple teams from a country to play in the UCL from the 1997-98 season, thus expanding the number of teams participating in the tournament.
As things stand, the Champions League main stage begins, with 32 teams divided into eight groups and the group stage will be played in a double round-robin. The top two teams from each group advance to the knockout rounds, which are played over two legs – except for the final. Domestic champions and runners-up from Europe's top football countries compete in the UEFA Champions League. Stronger leagues such as England, Spain and Germany can secure up to four places in the main draw. UEFA is considering expanding the number of teams to 48 to facilitate the participation of all countries.
Spanish giants Real Madrid won the first UCL (then known as the European Cup) in 1955 and went on to win the next four tournaments – the longest winning streak in the tournament's history. Defending champions Real Madrid have won the Champions League 14 times and are the most successful team in the Champions League. Italian club AC Milan is a close second with seven. Germany's Bayern Munich and England's Liverpool each won the annual title six times.
Meanwhile, Real Madrid's domestic rivals, Barcelona, have won five games. Ajax (4), Manchester United (3), Inter Milan (3), Juventus (2), Benfica (2), Nottingham Forest (2), Porto (2) and Chelsea (2) are other teams that have won multiple Champions Leagues. There have been 22 different UCL champions over the years.