A Casement is a window that is attached to its frame by one or more hinges. Casement windows are hinged at the side. Windows hinged at the top are referred to as awning windows, and ones hinged at the bottom are called hoppers.
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. 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. Casement windows are also excellent for natural ventilation strategies, especially in hot climates. They can be hinged to open outward and angled in order to direct breezes into the building.