Thai League 1, currently known as the Hilux Revo Thai League due to sponsorship, is the top professional football division in Thailand under the organization of the Football Association of Thailand. Since its professionalization in 1996, it has grown into one of Southeast Asia's most competitive and well-supported leagues. The league typically features 16 clubs playing a double round-robin schedule, with the season running from February to October. The champion qualifies for the AFC Champions League, while the bottom teams are relegated to Thai League 2. Headquartered in Bangkok, the league is known for its passionate fans, particularly at clubs like Buriram United, Muangthong United, and Bangkok United. Thai League 1 has seen increased investment, attracting foreign players and coaches, which has raised the overall standard. It is the primary source of players for the successful Thai national team and a central pillar of the country's sporting culture.