Major League Soccer (MLS) is a professional soccer league in the United States and Canada. Established in 1993, the league started play in 1996 with 10 teams. It has since expanded to 27 teams, with further expansion planned. MLS has played a significant role in growing the popularity of soccer in North America, attracting international players, and developing a strong youth system. The league operates on a franchise system with a salary cap and designated players who are exempt from the cap.