The UEFA Champions League is the pinnacle of club football. The tournament, formerly known as the European Cup, used to be only for the champions of each domestic league in Europe but it was gradually expanded to include more sides, to the point where there are now multiple teams from multiple countries competing each year.
It is, by some distance, the most important tournament in European football and qualification for the UEFA Champions League is a target for all top clubs each season and top players will regularly state the desire to play Champions League football as a reason for moving club.
The tournament itself has undergone many different changes since its introduction in 1992, when just eight teams made up two groups. The expanded nature of the competition means that there are now 32 teams that make up eight groups of four in the Champions League itself, with two from each group qualifying for the knock-out stages, which are two-legged matches all the way until the final, which is a one-off game.
Before the group stage is played, however, there are qualification rounds. These are for non-seeded teams from minor leagues or for teams that are non-champions in the major leagues. There are three qualification rounds in total, with different sides from different countries entering at various stages. The most high profile of these is the final stage where the fourth placed sides from England, Germany and Spain, as well as the third placed sides from France and Italy, join some of the champions from lesser domestic leagues in a play off to make the lucrative Champions League group stage.
Due to the nature of European football, and the key role that money plays in the sport at present, the UEFA Champions League has been dominated by sides from Spain, England, Germany and Italy. There has, in fact, only been four sides from outside those four countries that have contested Champions League finals, with Marseille and Ajax winning the trophy in the 90s and FC Porto beating AS Monaco in 2004. Since Porto's triumph every final has been between sides from Spain, England, Germany and Italy.
In recent seasons Spain's 'Big Two' have exerted even more dominance over the Champions League, with Real Madrid winning the competition in four of the last seven seasons. This, along with the fact that no side has ever retained the Champions League, is crucial to remember when placing your bets on the tournament.