UEFA Champions League is an annual club competition open to the champions and runners-up from Europe’s top national football leagues. The tournament is the most prestigious in European club football, and one of the most important competitions in world football. Its history is intertwined with some of the biggest names in football, including Real Madrid (five titles), Manchester United (three), Barcelona (four) and AC Milan (one).
The competition began as a simple knockout tournament between domestic champions until 1992 when it was renamed Champions League and introduced a group stage. Since then the competition has evolved into a more complicated format, which includes a preliminary round and a knockout phase that concludes with a final match between the two teams finishing top of their groups.
Teams are drawn into eight groups of four teams with home and away ties in a double round-robin format. Seeding is used during the draw for this stage, and teams from the same association may not be drawn against each other. Once the groups have been established, UEFA may reverse the order of legs in some ties due to scheduling and venue conflicts.
Champions League is the most popular European club competition among fans, and has seen a number of memorable moments over its long history. Some of the most notable include Porto’s shock victory in 2004, which marked the first time a non-top league club won the tournament; and Liverpool’s comeback win against AC Milan in the ‘Miracle of Istanbul’ in 2005, marking the first all-English final.