List of Major League Baseball annual home run leaders
In baseball, a home run is scored when the ball is hit so far that the batter is able to circle all the bases ending at home plate, scoring himself plus any runners already on base, with no errors by the defensive team on the play. An automatic home run is achieved by hitting the ball on the fly over the outfield fence in fair territory.
Source: Wikipedia — List of Major League Baseball annual home run leaders (CC BY-SA 4.0)