The Scottish Premier League (SPL) was the top professional football league in Scotland, established in 1998. It featured 12 teams competing annually for the championship title. The league operated on a system of promotion and relegation with the Scottish Football League, allowing the best teams to move up and the lowest-performing teams to drop down. In 2013, the SPL merged with the Scottish Football League to form the Scottish Professional Football League (SPFL). The SPL was known for its passionate fan base and historic clubs like Celtic and Rangers, which have a long-standing rivalry and dominate the league's history.