The NCAA basketball tournament existed long before the term "Final Four" was invented. It was played every year without millions of fans filling out their brackets. In 1939, the tournament was just another sports championship, with only eight teams, and was not very different than the playoffs of any other sport. But as time went on, the tournament grew, both in size and in meaning, as it became one of the biggest sports events of the year.
At first, the NCAA tournament did not even determine the national champion; the NIT Tournament did. But as the number of teams entered grew, so did the prestige of the tournament, and soon the NCAA overtook the NIT. The field expanded to 16 teams in 1951, and to 22 teams in 1953. The number of teams fluctuated between 22 and 25 between 1953 and 1974. In 1975, the tournament allowed 32 teams to enter, so that teams that did not win their conference could be chosen as at-large bids. Each conference was allowed two teams, with 16 teams qualifying as conference champions, four teams qualifying from regional tournaments conducted by the ECAC, and 12 teams selected at-large. This year was also the first time that the semifinals were officially referred to as the "Final Four," with the title appearing on multiple NCAA publications.
In 1978, a seeding process was used for the first time. Four teams in each region were granted automatic bids by winning their conference, and they were seeded based on their conference's win-loss record in the past five years of the tournament. The remaining teams were granted at-large bids, and seeded based on record and strength of schedule.
In 1979, the field was increased to 40 teams, with 24 teams being given first-round byes based on conference success in recent tournaments. The field grew again in 1980, to 48 teams. Twenty-four teams received automatic berths, and 24 were given at-large bids. 16 teams received a first-round bye.
In the early 1980s, new processes for selection of teams were implemented. In 1981, the Ratings Percentage Index (RPI) was created as a tool for ranking teams, particularly to determine at-large bids. Interest in the actual selection process grew, and in 1982, the "selection show" was broadcast on live national television. In 1983, five more teams were added to the field, making 53, the final number before the current bracket was created.
In 1985, the NCAA tournament took on the form in which it is known today, a 64-team tournament, in which every team must win the same number of games, six, to win the title. Thirty teams were automatic qualifiers, and 34 received at-large bids. Villanova, an 8 seed, was the first team to win a championship in the 64-team tournament, defeating Georgetown, 66-64.
The tournament remained at 64 teams until 2001, when a 65th team was added. This happened because of the creation of the Mountain West conference, which took up an additional automatic bid. The NCAA was hesitant to eliminate an at-large bid, however, which led to the odd number of teams. Now, every year, two teams from two of the less competitive conferences meet in Dayton, Ohio, and play for the right to enter the field of 64 as a No. 16 seed and play one of the top seeds.
Recently, many coaches have made the argument that the tournament needs to be expanded once again, due to the ever-increasing numbers of teams in Division I basketball. Syracuse coach Jim Boeheim, whose team was one of the "bubble" teams left out of the tournament in 2007, is one of the proponents of this expansion.