The NCAA Division I Men’s Basketball Tournament (known informally as March Madness or the Big Dance) is a single-elimination tournament played each spring in the United States, currently featuring 68 college basketball teams from the Division 1 level of the National Collegiate Athletic Association (NCAA), to determine the national championship. The tournament was created in 1939 by the National Association of Basketball Coaches, and was the idea of Ohio State University coach Harold Olsen. Played mostly during March, it has become one of the most famous annual sporting events in the United States.  The 68 teams are divided into four regions and organized into a single-elimination bracket.  Each team is “seeded”, or ranked, within its region from 1 to 16. A first round consisting of 64 teams playing in 32 games over the course of a week, the “Sweet Sixteen” and “Elite Eight” rounds the next week and weekend, respectively, and – for the last weekend of the tournament – the “Final Four” round. The Final Four is usually played during the first weekend of April. These four teams, one from each region (East, South, Midwest, and West), compete for the national championship.