西甲, or La Liga, is the top professional football division in Spain. Established in 1929, it features 20 teams competing annually for the championship title. The league is known for its high level of competition and has produced many world-class players and clubs. The most successful teams in 西甲 include Real Madrid and FC Barcelona, both of which have a rich history and a large fan base. The league operates on a promotion and relegation system with the second division, known as Segunda División, allowing for dynamic changes in team participation each season.