The Primera División (first division) is the top level of football in Argentina run by the Argentine Football Association, the league turned professional in 1931. The 20 teams in the Primera División play two single round tournaments each year.
From February to June the league is known as the Clausura and from August to December as the Apertura. Argentina holds no official knockout cup competiton. According to the latest statistics the Argentine league is rated as one of the top five in the world. Visit the official website and wikipedia if you want to learn more.