Coach Nana explains the basic Cover 2 defensive scheme, a zone coverage where the number "two" indicates there are two deep safeties. These safeties are responsible for the deep half of the field, and their main assignment is to ensure nobody gets past them. The corners cover a short zone, usually called the "flat," to cover all short routes in their area. The linebackers (or a nickel back) are responsible for the "hook to curl" zones, which are deeper than the flat. The Mike linebacker is responsible for the middle of the field. In this zone coverage, players are not assigned man-to-man but are instead responsible for specific zones, switching responsibilities as receivers run through their coverage areas.