A cornerback (CB) (also referred to as a corner) is a member of the defensive backfield or secondary in American and Canadian football. Cornerbacks cover receivers, to defend against pass offenses and make tackles. Other members of the defensive backfield include the safeties and occasionally linebackers. The cornerback position requires speed and agility. Since shorter players tend to be more agile than taller players, cornerbacks are typically among the shortest players on the team. A cornerback's skillset typically requires proficiency in anticipating the quarterback, back-pedalling, executing single and zone coverage, disrupting pass routes, shedding blockers, and tackling.