What is NCAA Division I men's basketball tournament?
{{Infobox sports league | title = | current_season = | last_season = | upcoming_season = | logo = March Madness logo.svg | logo_size = 200 | sport = Basketball | founded = {{start date and age|1939}} | inaugural = [[1939 NCAA basketball tournament|1939]] | country = United States | teams = 64 (Tournament) 8 (First Four) | most_champs = [[UCLA]] (11) | qualification = | tv = [[NCAA March Madness (TV program)|NCAA March Madness]]<br />([[CBS Sports|CBS]]/[[TBS (American TV channel)|TBS]]/[[TNT (American TV network)|TNT]]/[[TruTV]])<br />[[CBS Sports Network]] (re-airs)<br />[[Galavisión]] (Spanish-language) | streaming = | sponsor = | pyramid = | level = 1 | promotion = | relegation = | website = {{url|https://www.ncaa.com/sports/basketball-men/d1|ncaa.com/basketball}} }} The '''NCAA Division I men's basketball tournament''' (also known as '''March Madness''') is a [[Single-elimination tournament|single-elimination]] (if you lose a game, you stop playing) college basketball [[tournament]]. It has 68 college teams in it. The [[National Collegiate Athletic Association]] (NCAA) created it in 1939. When it was started in 1939, only eight teams played in the tournament. The tournament is played from mid-March to early April. 32 of the teams in the tournament are the best teams in each Division I [[Athletic conference|conference]]. 36 of the teams join the tournament by winning other basketball games. These teams are chosen by the NCAA to be in the tournament. For the tournament, there are four regions. Each team is put into a [[region]]. Each region has 16 teams. The tournament has seven rounds. It is three weeks long. The first round is called the First Four. It has eight teams in it. The four winning teams join the tournament. Each team is given a number. It is from 1 to 16. In the tournament, the semifinals are known as the Sweet Six