At-large bid

An at-large bid is a bid or berth in a sporting tournament granted by invitation, not right. This term is most commonly used in the United States to refer to berths that the NCAA grants in its annual Division I men's and women's basketball tournaments, although at-large berths are granted in almost all championship tournaments the NCAA conducts.

The NIT, held for the best teams that didn't make the NCAA Tournament, was at one time an entirely at-large event (hence its name, the National Invitation Tournament); new regulations, however, offer automatic bids to teams regular season conference champions which failed to win their post-season conference tournament. The College Basketball Invitational and CollegeInsider.com Postseason Tournament both seed their entire tournaments with at-large bids.

This article focuses mainly on the most common use of the term, in reference to the basketball tournaments. However, a similar procedure applies in most other NCAA-sponsored tournaments, and in other tournaments that use an NCAA-style system.

Each year, the NCAA grants automatic berths in both the men's and women's Division I basketball tournaments to the winners of 31 conferences. In all cases, the conference's automatic berth is granted to the team that wins its conference postseason tournament, with the sole exception of the Ivy League, which has never conducted a postseason tournament. The Ivy League berth is granted instead to the regular-season champion.

The NCAA has established Selection Committees for both the men's and women's tournaments. Teams that did not win their conference tournament may be eligible to earn an at-large berth. At-large berths are determined by record, ranking, strength of schedule, and many other factors. A key factor in determining at-large berths is the Ratings Percentage Index, popularly referred to as the RPI.

...
Wikipedia