A cornerback is a position in American football primarily responsible for covering wide receivers and defending against passing plays. They line up on the outside of the defensive formation and use their speed and agility to stay close to the receiver, aiming to prevent them from catching the ball. Cornerbacks must also be skilled in tackling and reading the quarterback's intentions. In addition to pass coverage, cornerbacks play a crucial role in run defense. They often need to support their teammates by tackling ball carriers who break through the defensive line. Successful cornerbacks, like Deion Sanders or Darrelle Revis, are known for their ability to anticipate plays and make game-changing interceptions.