A casement is a window that is attached to its frame by one or more hinges at the side. They are used singly or in pairs within a common frame, in which case they are hinged on the outside. Casement windows are often held open using a casement stay.
Casement windows are hinged at the side and open outward, to the left or to the right. They are available in one, two, three, four or five-lite configurations. Casement windows are made for openings in which the height is greater than the width. However, awning windows are hinged at the top and are only available in one, two or three-lite configurations. Awning windows are made for openings in which the width is greater than the height.