A defensive line is a group of players in American football positioned at the front of the defense. Their primary role is to stop the opposing team's offensive plays, particularly by tackling the quarterback or halting running plays. The defensive line typically consists of defensive tackles and defensive ends, who work together to create pressure and disrupt the offense. These players must be strong and agile, as they face off against the offensive line, which aims to protect the quarterback and create openings for running backs. Effective defensive lines can significantly impact the game's outcome by forcing turnovers and limiting the opponent's scoring opportunities.