Wild card: In playing card terms, a wild card is a card that can be assigned any value its holder desires. A wild card can be a pre-assigned card, such as any 2 (deuce) or the jack of spades, for example, or a special card, usually one of the jokers.
In sport, the term "wild card" refers to a team that qualifies for that sporting league's (association, etc.) playoffs that is one of several high achieving teams that did not obtain the best win-loss record in their specific subdivision (usually called a conference or division) of that sport's league. The number of wild card teams varies depending on the rules of the particular sport's league. In most cases, the rules of the league call for the wild card team to be intentionally placed at an inherent disadvantage before the start of the playoff tournament, either by having to survive an extra round and/or being made to play the majority of their potential postseason games on the road.
In Major League Baseball, for example, the wild card team must surrender the home field advantage in the Divisional Series (ALDS and NLDS) and League Championship Series (ALCS and NLCS). Regardless, however, of how the League Champion team reaches the World Series, the home field advantage for the World Series has been determined beforehand (prior to 2003, on an alternating schedule; in 2003 and 2004 the home field advantage was determined by the winner of the All-Star Game). A controversy resulted in 1997 when the Florida Marlins, who won the National League pennant after qualifying for the playoffs as a wild card, had home-field advantage over the AL champion Cleveland Indians, who had won their division, in that year's World Series, which the Marlins won in seven games, winning the seventh and deciding game at home. Both of the teams that reached the 2002 World Series were wild card teams: The Anaheim Angels from the AL and the San Francisco Giants from the NL. The Angels won the series in seven games.