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.
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.
Home runs are among the most popular aspects of baseball, and the biggest stars are typically the players who hit many of them.
The all-time career record for home runs in the Major Leagues is 755, held by Henry Aaron. Only two other players have hit as many as 600, Babe Ruth (715), and Willie Mays (660). The single season record is 73, set by Barry Bonds in 2001.