Official game
An official game in baseball, also sometimes called a regulation game, is a game that has progressed beyond the point at which it can be considered complete if necessary. This is approximately the halfway point of the game. In the case of inclement weather, any game which has reached this point may be stopped and shortened as needed, with the result being final, and all records and statistics counted. A game which has not reached this point before being stopped is either considered a suspended game (to be continued at a later date from the point of stoppage), or is simply canceled and replayed from the start. (This depends on the rules of each individual league.) In either case, no statistics are counted until the game becomes official.
Since most professional baseball games are nine innings long, the fifth inning is used as the threshold for an official game. If the visiting team is leading, or the game is tied, the end of the fifth inning marks this point. If the home team (which bats last) is already ahead in the score, and theoretically would not need its half of the fifth inning, then 4½ innings (i.e., the middle of the fifth) is considered an official game. The game is also considered official if the home team scores to take the lead in the bottom of the fifth inning, since the game would end immediately if the same thing happened in the ninth.
In nearly all cases, the "official game" status is used to determine whether a rain check will be honored for fans holding tickets. If a game is started but does not reach the point of becoming official, fans are entitled to a new ticket for the make-up game or (in most cases) any other available game of their choice. If a game is halted after it becomes official, the game is simply shortened and no rain check is given.
The "official game" statistic received some attention during the 1995 season, when Cal Ripken, Jr. was approaching the record for consecutive games played, previously held by Lou Gehrig. Large numbers were hung on the side of the B&O Warehouse at Oriole Park at Camden Yards to show the number of games in Ripken's streak. Each day, a new number was unfurled during the fifth inning after each game had become official (since the statistic would not have counted if the game had been stopped before that point). A similar practice has been used to count down toward the demolition of several stadiums (including Veterans Stadium in Philadelphia in 2003, Busch Memorial Stadium in St. Louis in 2005, and the original Yankee Stadium and Shea Stadium in New York City in 2008); as each game became official, the team would unveil a new (lower) number showing the number of games left to be played in the stadium.
Other sports
Other professional sports utilize similar rules regarding "official" games/events.
Most codes of motorsport declare a race "official" with an official result if just three laps are completed, though only half the normal championship points are awarded if less than 75% of the race distance (rounded up to the nearest whole lap) is completed. If more than 75% of the race is completed, full points are awarded.
The major exception applies in the United States, mainly in NASCAR and INDYCAR, where races must go at the next full lap after halfway. A race is considered "official" if it has completed half the scheduled distance plus one additional lap. For instance, the Indianapolis 500 (200 laps) must complete 101 laps to be considered official.