La Liga (Campeonato Nacional de Liga de Primera División) 

La Liga is the Spanish football league in the top division, existed since 1929. The second is called Segunda División. Since 1997, there are 20 clubs participating in the top league of La Liga which has been organized by Liga de Fútbol Profesional (LFP).

Most championships winning to date is Real Madrid (33)
Most played seasons are Barcelona, Real Madrid (88)

History
The first soccer league in Spain was The Catalan football championship (Campionat de Catalunya), founded in 1901. After the establishment of the La Liga, The Catalan football championship still included in the national league for a few years until it was cancelled in 1940.

The first season of La Liga started in February 1929 and ended in June). At this time, it consisted of one division, Primera División, and consisted of ten clubs. The numbers of clubs would later increased at several occasions. In 1987, it reached 20 clubs and that have remained stable except a short period (1995-1997) with 22 clubs.

League system
The first and second division was founded at the same time in 1929. In 1977, Segunda División B, was created to replace Tercera División as the third tier. Tercera División has since become the fourth tier. 
Qualification for European Cups
Nowadays, the top four teams in La Liga are qualified for competing in the Champions League and the team that is placed fifth will get the chance to compete in Europa League (another place also goes to the winner of the Copa del Rey).

Relegations
Nowadays, the three teams placed at the bottom of the table (places 18-20) will be relegated to Segunda División.
Teams with most titles
Real Madrid and Barcelona has been dominated the Spanish football league. Between the first season in 1929 to season 2016-2019 they won total of 60 of the 89 possible trophies.