The playoffs, postseason or finals of a sports league are a competition played after the regular season by the top competitors to determine the league champion or a similar accolade. Depending on the league, the playoffs may be either a single game, a series of games, or a tournament, and may use a single-elimination system or one of several other different playoff formats. Playoff, in regard to international fixtures, is to qualify or progress to the next round of a competition or tournament.
In team sports in the U.S. and Canada, the vast distances and consequent burdens on cross-country travel have led to regional divisions of teams. Generally, during the regular season, teams play more games in their division than outside it, but the league’s best teams might not play against each other in the regular season. Therefore, in the postseason a playoff series is organized. Any group-winning team is eligible to participate, and as playoffs became more popular they were expanded to include second- or even lower-placed teams – the term “wild card” refers to these teams.
In England and Scotland, playoffs are used in association football to decide promotion for lower-finishing teams, rather than to decide a champion in the way they are used in North America. In the EFL Championship (the second tier of English football), teams finishing 3rd to 6th after the regular season compete to decide the final promotion spot to the Premier League. Wikipedia.