In baseball, a home run is a base hit in which the batter is able to circle all the bases, ending at home plate and scoring a run, with no errors on the play.
Home runs are among the most popular aspects of baseball, and the biggest stars are typically the players who hit many of them.
In almost all cases, a home run involves hitting the ball over the outfield fence. Very rarely, a batter can hit the ball in play and circle all the bases before the fielders can stop him; this is called an inside-the-park home run, and typically requires that the fielder misplay the ball in some way, or that the ball is made difficult to play by caroming in unexpected ways or by getting caught in something. If the misplay is labeled an error by the official scorer, however, the batter is not credited with a home run. A grand slam home run occurs when the bases are "loaded" (that is, there are players standing on first, second, and third base) and the batter hits a home run.
Prior to 1931, a ball that bounced over an outfield fence during a Major League Baseball game was considered a home run. The rule was changed to require the ball to clear the fence on the fly, and balls which reached the seats on a bounce became ground-rule doubles in most parks.
The all-time career record for home runs in Major League Baseball is 755, held by Hank Aaron. Only three other Major League Baseball players have hit as many as 600, Babe Ruth (714), Willie Mays (660), and Barry Bonds (658). The single season record is 73, set by Barry Bonds in 2001.
Other home run legends include Ted Williams, Mark McGwire, Sammy Sosa, Mickey Mantle, Reggie Jackson, Josh Gibson, Ernie Banks, Eddie Mathews and Sadaharu Oh.
Slang terms for home runs include: big-fly, bomb, dinger, blast, clout, four-bagger, homer, jack, shot, moonshot, round-tripper, swat, tater.
A game with many home runs in it can be referred to as a slugfest.
Player nicknames that describe homerun-hitting prowess include:
Home run also refers to a cable configuration where cable runs from a central location to each device individually, i.e. a Star Topology as opposed to a Daisy Chain Topology.