The UEFA Champions League is an annual continental club football competition organised 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 (and, for some nations, one or more runners-up) of the strongest UEFA national associations. The UEFA Champions League final is the most watched annual sporting event worldwide. The final of the 2012–13 tournament had the highest TV ratings to date, drawing 360 million television viewers.

Real Madrid is the most successful club in the competition's history, having won the tournament 12 times, including its first five seasons. Spanish clubs have accumulated the highest number of victories (17 wins), followed by England and Italy (12 wins apiece). The competition has been won by 22 different clubs, 12 of which have won it more than once. The reigning champions are Real Madrid, who secured their twelfth title in the competition after defeating Juventus 4–1 in the 2017 final. Thus, they became the first team in the UEFA Champions League era to successfully defend their title.

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