Double-hung sash windows were traditionally often fitted with shutters. Sash windows can be fitted with simplex hinges that let the window be locked into hinges on one side, while the rope on the other side is detached—so the window can be opened for fire escape or cleaning.
A sash window is the traditional style of window in the United Kingdom, and many other places that were formerly colonized by the UK, with two parts (sashes) that overlap slightly and slide up and down inside the frame. The two parts are not necessarily the same size; where the upper sash is smaller (shorter) it is termed a cottage window. Currently most new double-hung sash windows use spring balances to support the sashes, but traditionally, counterweights held in boxes on either side of the window were used. These were and are attached to the sashes using pulleys of either braided cord or, later, purpose-made chain. Three types of spring balances are called a tape or clock spring balance; channel or block-and-tackle balance; and a spiral or tube balance.
The English language-word window originates from the Old Norse 'vindauga', from 'vindr – wind' and 'auga – eye', i.e., wind eye. In Norwegian Nynorsk and Icelandic the Old Norse form has survived to this day (in Icelandic only as a less used word for a type of small open "window", not strictly a synonym for gluggi, the Icelandic word for window), in Swedish the word vindöga remains as a term for a hole through the roof of a hut, and in the Danish language 'vindue' and Norwegian Bokmål 'vindu', the direct link to 'eye' is lost, just like for 'window'. The Danish (but not the Bokmål) word is pronounced fairly similarly to window.
A window is an opening in a wall, door, roof or vehicle that allows the passage of light, sound, and air. Modern windows are usually glazed or covered in some other transparent or translucent material, a sash set in a frame in the opening; the sash and frame are also referred to as a window. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather. Windows often have a latch or similar mechanism to lock the window shut or to hold it open by various amounts.