La Liga, or as it is officially called the Primera Division, was founded in 1929 and is the top level of Spanish soccer. It is the most successful league in Europe with La Liga teams having won more UEFA Champions League/European Cups, UEFA Europa League, UEFA Super Cup, and FIFA Club World Cup titles than any other European league.
9 clubs have won the title over the course of history with Real Madrid the most successful club followed closely by Barcelona. Atlético Madrid, Valencia, Deportivo de La Coruña, Athletic Bilbao, Real Sociedad, Sevilla, and Real Betis have also won titles.
The 20-team competition features 380 matches (each team plays every other team home and away during a season) between August and May with teams earning 3 points for a win, 1 point for a draw, and 0 points for a loss.
Surprisingly and unique for European domestic leagues, the winner does not receive the winner’s trophy until their first home game of the following season. That tradition was started to avoid having to have multiple trophies on hand if more than 1 club could win the title on the final matchday. But it is frustrating for the modern game as frequently players have moved to new clubs before they can celebrate with the trophy.
The winner, runner-up, and 3rd place finisher automatically qualify for the UEFA Champions League group stage while the 4th place team enter the final qualifying round for the Champions League. The 5th and 6th place teams qualify for the UEFA Europa League and the 7th place team qualifies as well in the case of the Copa del Rey finalist both finishing in the top 6.
After each season, the bottom 3 teams are relegated to the Segunda Division. They are replaced in the 20-team league with the top 2 finishers from the Segunda Division as well as the playoff winner between the 3rd, 4th, 5th and 6th place teams.