Sash
Glass and framing make up a window sash, which is sometimes movable and sometimes fixed
A sash on a window is made up of a pane or multiple panes of glass and the overall framework containing the panes. The framework of a sash is made up of muntins, rails and stiles.
A sash can travel vertically in channels on the left and right sides of the window frame. A single-hung window is made up of a fixed top sash and movable bottom sash. On a double-hung window, both the top and bottom sash can move.
A sash can travel vertically in channels on the left and right sides of the window frame. A single-hung window is made up of a fixed top sash and movable bottom sash. On a double-hung window, both the top and bottom sash can move.
The lower sash is positioned closest to the interior of a room.
Open the sash and you let in fresh air.