what is an unearned run

An unearned run in baseball is a run that scores as a direct result of a defensive error or a passed ball. It is a run that would not have scored if the defense had played perfectly without mistakes. The official scorer determines whether a run is unearned by reconstructing the inning as it would have occurred without errors or passed balls. Unearned runs do not count against a pitcher's earned run average (ERA), which measures the runs a pitcher is personally responsible for allowing. However, unearned runs still count toward the team's total score and can impact the game outcome. Essentially, an unearned run is "given away" by the defense rather than earned by the offense through normal play