In professional sports, this occurs when a league decides to change which teams are in which divisions, usually by creating new divisions. In all of the four major North American sports leagues, all of the teams are grouped into one of two conferences (or leagues in baseball) while each conference/league is further subdivided into divisions. Teams in the same division play each other more regularly than teams in the same conference, and much more often than teams in the other conference. Teams from the same division can form intense rivalries. The top team from a division is always guaranteed a playoff spot and guaranteed a higher seeding in the playoffs. Divisions are usually based on geography, both to minimise travel costs and to encourage regional rivalries.