A casement window (or casement) is a window that is attached to its frame by one or more hinges.[1] Casement windows typically are hinged at the side, sometimes at the top or bottom. They are used singly or in pairs within a common frame, in which case they are hinged on the outside.
Casement windows were the most common house window before the sash window was introduced, and usually contain leaded glass.[2] These casement windows usually were hinged on the side, and opened inward. The windows were covered by functional exterior shutters, which opened outward.