The National Football League (NFL) is the United States' premier professional American football league, formed in 1920 as the American Professional Football Association (APFA) before being renamed in 1922. Comprising 32 teams equally divided into two conferences, its 18-week regular season leads to a thrilling playoff tournament, culminating in the Super Bowl each February between the conference champions. This iconic championship game was first held in 1967 following an agreement to merge the NFL with the rival American Football League (AFL), becoming the league's ultimate contest after the merger's completion in 1970. Globally, the NFL is renowned as the wealthiest professional sports league, boasting the highest average attendance, and is the most popular sports league in the United States, with Super Bowl broadcasts consistently breaking viewership records. Historically, the Green Bay Packers hold the most combined NFL championships with thirteen, while the New England Patriots and Pittsburgh Steelers share the record for most Super Bowl victories with six apiece.