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:
Progression of the Single-Season Home-Run Record
List of lifetime home run leaders through history
- 5, by George Hall, Phinadelphia Athletics (NL), 1876 (70 games)
- 9, by Charley Jones in 1879
- 14, by Harry Stovey, 1883
- 27, by Ned Williamson, Chicago White Stockings (NL), 1884
- Williamson benefitted by a short outfield fence in his home ballpark. The year before and the year afterward, balls hit over that fence in that park were ground-rule doubles, but in 1884 they counted as home runs. Williamson led the pace, but several of his Chicago teammates also topped the 20 HR mark that season. Noticing the fluke involved, fans of the early 20th century were more impressed with Buck Freeman's total of 25 home runs in 1899 or Gavy Cravath's 1915 total of 24.
- 29, by Babe Ruth, Boston Red Sox (AL), 1919
- 54, by Ruth, New York Yankees (AL), 1920
- Ruth hit nearly the same number of home runs on the road in 1920 as he did in 1919, but hit far more in the Polo Grounds in New York (where the Yankees played at the time) than he did in Fenway Park in Boston the year before.
- 59, by Ruth, New York (AL), 1921
- 60, by Ruth, New York (AL), 1927
- Ruth hit more home runs in 1927 than each of the other seven American League teams. His closest rival was his teammate, Lou Gehrig, who hit 47 homers that year.
- 61, by Roger Maris, New York (AL), 1961
- Pushing Maris that year was teammate Mickey Mantle; slowed by an injury late in the season, Mantle finished with 54.
- 70, by Mark McGwire, St. Louis Cardinals (NL), 1998
- Pushing McGwire that year was Sammy Sosa of the Chicago Cubs, who finished with 66.
- 73, by Barry Bonds, San Francisco Giants (NL), 2001
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.