Inside-the-park home run

In baseball, an inside-the-park home run is a play where a batter hits a home run without hitting the ball out of the field of play. It is also known as an "in-the-park home run" or "in the park homer".

To score an inside-the-park home run, the player must touch all four bases (in the order of first, second and third, ending at home plate) before a fielder on the opposing team tags him out. In Major League Baseball, if the defensive team commits an error during the play, it is not scored as a home run, but rather advancing on an error. Statistically, an inside-the-park home run counts as a regular home run in the player's season and career totals.

The vast majority of home runs occur when the batter hits the ball beyond the outfield fence on the fly; this is purely a feat of hitting with power, along with a fortuitous flight angle of the ball. The inside-the-park home run is of a very different character; it is primarily a feat of fast baserunning, though strong hitting is also typically involved.

In the early days of Major League Baseball, with outfields more spacious and less uniform from ballpark to ballpark, inside-the-park home runs were common. However, in the modern era, with outfields less spacious, the feat has become increasingly rare, happening only a handful of times each season. Today an inside-the-park home run is typically accomplished by a fast baserunner hitting the ball in such a way that the ball bounces far away from the opposing team's fielders. In many such cases (such as Alcides Escobar's inside-the-park homer in the 2015 World Series), the outfielder misjudges the ball or otherwise plays it badly, but not so badly that an error is charged.

Of the 154,483 home runs hit between 1951 and 2000, 975 (about 1 in every 158) were inside-the-park. The percentage has dwindled since the increase in emphasis on power hitting which began in the 1920s.

...
Wikipedia