<human>:  What is the history of the Champions League?
<bot>: The UEFA Champions League is an annual club football competition organized by the Union of European Football Associations (UEFA) and contested by top-division European clubs. It is one of the most prestigious tournaments in the world and the most prestigious club competition in European football, played by the national league champions of their national associations. The competition started in its current format in 1992, when it was named the UEFA Champions League. Prior to 1992, the competition was named the European Champion Clubs' Cup, which was first held in 1955. The Champions League is open to the champions of all UEFA member associations and a number of clubs that finish clubs with the highest coefficients in the previous season. Each season, the clubs compete directly in a double round-robin group stage, before progressing to a knock-out competition, and the winner usually coincides with the reigning European champion.