A casement window is a window that is attached to its frame by one or more hinges. Casement windows are hinged at the side. They are used singly or in pairs within a common frame, in which case they are hinged on the outside.
They are opened with a crank, lever, or cam handle, which is placed around hand height or at the bottom and serves as a window lock. A crank, stay, or friction hinge is necessary when the window opens outward, to hold the window in position despite wind. Often the glass panes are set in a rabbeted frame and sealed with beveled putty or glazing compound to secure the glass.