The term given to Major League Baseball's All-Star Game, which takes place annually at the midpoint of the regular baseball season. The National League and American League each field a team, selected by a combination of fans, coaches and managers.
The All-Star Game is an exhibition game, and is not statistically counted as part of the regular season (player's statistics are not affected in any way). Because the mid-Summer Classic is meant to feature the best in baseball, the players selected generally have high statistics for their positions. This does not mean that the statistically best players are always selected to the All-Star Game, however, as a large portion of the players are determined exclusively by fans, sometimes resulting in popularity winning out over performance.
The managers of each All-Star team are always the managers who appeared in the previous year's World Series (Fall Classic). These managers have some discretion over their rosters, filling the final spots, and often select players from the team they manage, or players they have a particular preference for.
In order to give more meaning to the All-Star Game beyond just exhibition, the MLB instituted a rule, beginning in 2003, that the winner of the mid-Summer Classic would claim home-field advantage in the World Series.