In baseball, an earned run is any run that was fully enabled by the offensive team's production in the face of competent play from the defensive team. Conversely, an unearned run is a run that would not have been scored without the aid of an error or a passed ball committed by the defense; it is "unearned" in that it was, in a sense, "given away" by the defensive team.
Earned and unearned runs count equally toward the game score; the difference is purely statistical. Both total runs and earned runs are tabulated as part of a pitcher's statistics, but earned runs are specially denoted because of their use in calculating a pitcher's earned run average (ERA), the number of earned runs allowed by the pitcher per nine innings pitched (i.e., averaged over a regulation game). Thus, in effect, the pitcher is held personally accountable for earned runs, while the responsibility for unearned runs is shared with the rest of the team.
