Serie A (Italian pronunciation: [ˈsɛːrje ˈa]), also called Serie A TIM due to sponsorship by Telecom Italia, is a professional league competition for football clubs located at the top of the Italian football league system and has been operating for over eighty years since the 1929-30 season. It had been organized by Lega Calcio until 2010, but a new league, the Lega Serie A, had been created for the 2010–11 season. Serie A has produced the highest number of European Cup finalists: Italian clubs have reached the final of the competition on a record twenty-six different occasions, winning the title twelve times. Serie A is ranked 4th among European leagues according to UEFA's league coefficient behind the English Premier League, Spanish La Liga, and German Bundesliga, which is based on the performance of Italian clubs in the Champions League and the Europa League. It also ranked 5th in world according to the first trends of the 2011 IFFHS rating.

In its current format, the Italian Football Championship was revised from having regional and interregional rounds, to just one solid league from the 1929–30 season onwards; the Serie A system carries on today. The championship titles won before 1929 are officially recognised by FIGC as a championship in the same way the ones since then are. The 1945–46 season, when the league was played over two geographical groups due to WWII destructions, is not statistically considered, even if its title is fully official.