A type of home run that occurs when the batter hits the ball into the field of play but is able to round all of the bases safely without being tagged out. If the batter reaches home due to a fielding error, such as a missed pass, the play will not be recorded as a home run. This type of homer occurs far less frequently than a traditional home run that sees the ball leave the field of play over the outfield fence leading to an automatic home run.
Also known as a "Leg Home Run."
Inside-the-Park Home Runs are generally scored when the batter hits the ball with strength down the line or in the gaps and is a very fast runner and they will often see some mishandling of the ball by the outfield but not enough to incur an error.
The Inside-the-Park homers happened far more often in the earlier days of baseball due to the greater field lengths in the past compared to the shorter fields seen in modern day baseball.
Inside-the-Park Home Run Records