Each MLB league (American and National) has three divisions (West, Central and East). Each of these divisions has four, five or six teams. Throughout the course of a 162-game season, teams in each division play all other teams in their own league and some from the other league, with a majority of their games against teams in their own divisions. The team with the best overall record in each division makes the playoffs as a division champion. Wild Card teams cannot be division champions.
Determining the Wild Card
Once a second place division team is out of the hunt for their respective division championship, their record is compared to each other second place team in their league. The team with the best overall record wins the wild card. If two teams have identical records, they play in a one-game playoff to determine the wild card champion. If three or more teams have identical records, then tie-breaking rules determine which of the tied teams would face off to determine who earned the wild card berth.
The Wild Card Round
Once all four teams from each league have reached the playoffs, they face off in the Wild Card round of the MLB playoffs. Four different two-team "best of five" series begin, with the first two games of each being played at the higher seeded team's stadium. Wild Card teams are automatically the lower seed in their series, even if they have a higher record than the division winner they are facing. The next two games are then played at the lower-seeded team's stadium with fifth (if necessary) games played back at the higher-seeded team's stadium.