What is a nickelback in football?

In football, a nickelback is a defensive back who comes into play when a team employs a "nickel" defensive formation, typically involving five defensive backs instead of the usual four. This player often covers slot receivers and is responsible for defending against short passes and quick routes. The nickelback needs to be versatile, as they must be effective in both coverage and run support. The position has become increasingly important in modern football due to the prevalence of passing plays.