Major League Baseball Wild Card game

The Major League Baseball Wild Card Game is a play-in game which was added to the Major League Baseball postseason in 2012. The addition keeps the playoff format similar to the three-tiered postseason format used from 1994 through 2011, but adds a second wild-card team. Two wild-card teams in each league play each other in a single-game playoff after the end of the regular season. The winner of the game advances to the 1st seeded team in the Division Series. The home team for the wild-card game is the team with the better regular-season record (4th Seed).

If both teams have the same number of wins and losses, tie-breaking procedures are used, with no additional games being played. On the other hand, teams tied for the division title will now always play a one-game playoff for the division title, even if both teams are already qualified for the postseason. This is in contrast to the earlier wild card format used, for example in the 2005 season when the New York Yankees and Boston Red Sox tied for first place in their division but did not play an additional game as both teams were qualified for the postseason in any event.

In the division series, the winner of the wild-card game will always face whichever division champion has the best record. All division winners receive a bye as they await the result of the game. Previously, a wild-card team could not face the champion of its own division. This change makes it possible for the two teams with the best record in the league to face each other before the League Championship Series for the first time since 1997 (from 1994 to 1997 the matchups for the division series were determined by annual rotation between the west, central and east divisions).

The addition of a second wild-card team to each league was completed for multiple reasons:

With the adoption of MLB's new collective bargaining agreement in November 2011, baseball commissioner Bud Selig announced that a new playoff system would begin within the next two years; the change was ultimately put into place in 2012.

...
Wikipedia