An official game is a game that has been played to a final result and counts in the standings, and whose statistics also count, even if it has not gone its full scheduled length. A 9-inning game becomes "official" after 4 1/2 innings when the home team leads, after 5 innings if either the game is tied or the road team leads or, finally, upon the home team assuming the lead in the bottom of the 5th. No matter what happens after that point, the statistics accumulated and the result of the game will be counted. Before 2007, tied called games of official length sometimes resulted in players (and teams) playing more than 162 games in a season, as such games were officially part of accumulated players' statistics but were replayed from the beginning; with the change in the rules, tie games are still possible, but only under very exceptional circumstances. In contrast, games called before becoming official result in the events of the game simply being wiped out of the official statistical record, as if they never happened. This is covered in section 4.10 of the official rules, where an official game is called a "regulation game".
The question of whether a game is "official" comes into play when it is threatened to be ended early by weather. The team that is leading will try to play as quickly as possible in order to ensure the game reaches the point where it is official and its lead becomes a win, while on the other hand the team that is losing has no such interest and may try to stall so that the umpires stop play. However, if a team takes stalling actions that are too obvious, the umpire can rule a forfeit and grant the victory to the team that is leading, even if the game is not yet official.
Another situation where the point a game becomes official is important is in determining certain streaks. For example, if a player extends a hitting streak in the early innings of a game threatened by weather, one can be certain that he has actually extended the streak only at the point the game becomes official; if it ends before, the hit is wiped out. Another example is when Cal Ripken broke Lou Gehrig's record for consecutive games played on September 6, 1995; the game was interrupted at the point it became an official game to honor Ripken, as it became certain that the game would count and that he had set a new record.
It is common for players to see good performances wiped out because a game was called before it became official; Retrosheet for example keeps a list of players who have lost homers in these circumstances.
- A list of "lost home runs" from retrosheet.org