The window frame is the enclosure that holds the main parts of a window-- called window sashes--in place. Window sashes may be fixed or operable. Obviously, in a fixed window the sashes don't move. But operable windows employ several methods for window sash movement. With single- and double-hung windows, the sashes slide up and down. With casement windows, they swing in or out from the frame. Sliders slide. And so forth. For more about various types of windows, see Types of Windows.