A window is a transparent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like a float glass. Windows are held in place by frames, which prevent them from collapsing in. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather.

　　The 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 Swedish the word vind?ga remains as a term for a hole through the roof of a hut, and in the Danish language vindue and Norwegian Bokm?l vindu, the direct link to eye is lost, just like for window. The Danish word is pronounced fairly similar to window.

　　Window is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. Window replaced the Old English eagtyrl, which literally means eye-hole, and eagduru eye-door. Many Germanic languages however adopted the Latin word fenestra to describe a window with glass, such as standard Swedish f?nster, or German Fenster. The use of window in English is probably due to the Scandinavian influence on the English language by means of loanwords during the Viking Age. In English the word fenester was used as a parallel until the mid-18th century and fenestration is still used to describe the arrangement of windows within a fa?ade.

　　From Websters 1828 Dictionary: Window, n.

　　History of window

　　Primitive windows were just holes in a wall. Later, windows were covered with animal hide, cloth, or wood. Shutters that could be opened and closed came next. Over time, windows were built that both protected the inhabitants from the elements and transmitted light: mullioned glass windows, which joined multiple small pieces of glass with leading, paper windows, flattened pieces of translucent animal horn, and plates of thinly sliced marble. The Romans were the first to use glass for windows. In Alexandria ca. 100 CE, cast glass windows, albeit with poor optical properties, began to appear. Mullioned glass windows were the windows of choice among European well-to-do, whereas paper windows were economical and widely used in ancient China, Korea and Japan. In England, glass became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century in Northern Britain. Modern-style floor-to-ceiling windows became possible only after the industrial glass making process was perfected.

　　Types of windows

　　Double-hung sash window

　　This sash window is the traditional style of window in the USA, and many other places that were formerly colonized by the UK, with two parts that overlap slightly and slide up and down inside the frame. The two parts are not necessarily the same size. Nowadays, 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. Double-hung sash windows were traditionally often fitted with shutters. Sash windows may be fitted with simplex hinges which allow the window to be locked into hinges on one side, while the rope on the other side is detached, allowing the window to be opened for escape or cleaning.

　　Single-hung sash window

　　One sash is movable and the other fixed. This is the earlier form of sliding sash window, and is also cheaper.

　　Horizontal sliding sash window

　　Has two or more sashes that overlap slightly but slide horizontally within the frame. In the UK, these are sometimes called Yorkshire sash windows, presumably because of their traditional use in that county.

　　Casement window

　　A window with a hinged sash that swings in or out like a door comprising either a side-hung, top-hung , or occasionally bottom-hung sash or a combination of these types, sometimes with fixed panels on one or more sides of the sash. In the USA, these are usually opened using a crank, but in parts of Europe they tend to use projection friction stays and espagnolette locking. Formerly, plain hinges were used with a casement stay. Handing applies to casement windows to determine direction of swing; a casement window may be left-handed, right-handed, or double. The casement window is the dominant type now found in the UK and parts of Europe.

　　Awning window

　　An awning window is a casement window that is hung horizontally, hinged on top, so that it swings outward like an awning.

　　Hopper window

　　A hopper window is a bottom hung casement window that opens similar to a draw bridge typically opening to the outside.

　　Tilt and slide window

　　A window where the sash tilts inwards at the top and then slides horizontally behind the fixed pane.

　　Tilt and turn window

　　A window which can either tilt inwards at the top, or can open inwards hinged at the side.

　　Transom window

　　A window above a door; in an exterior door the transom window is often fixed, in an interior door it can open either by hinges at top or bottom, or rotate on hinges. It provided ventilation before forced air heating and cooling. A fan-shaped transom is known as a fanlight, especially in the British Isles.

　　Jalousie window

　　Also known as a louvered window, the jalousie window consists of parallel slats of glass or acrylic that open and close like a Venetian blind, usually using a crank or a lever. They are used extensively in tropical architecture. A jalousie door is a door with a jalousie window.

　　Clerestory window

　　A window set in a roof structure or high in a wall, used for daylighting.

　　Skylight

　　A flat or slope window used for daylighting, built into a roof structure that is out of reach.

　　Roof window

　　A roof window at the Muse du Louvre A sloped window used for daylighting, built into a roof structure.

　　Roof lantern

　　A roof lantern is a multi-paned glass structure, resembling a small building, built on a roof for day or moon light. Sometimes includes an additional clerestory. May also be called a cupola.

　　A window is a transparent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like a float glass. Windows are held in place by frames, which prevent them from collapsing in. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather.

　　The 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 Swedish the word vind?ga remains as a term for a hole through the roof of a hut, and in the Danish language vindue and Norwegian Bokm?l vindu, the direct link to eye is lost, just like for window. The Danish word is pronounced fairly similar to window.

　　Window is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. Window replaced the Old English eagtyrl, which literally means eye-hole, and eagduru eye-door. Many Germanic languages however adopted the Latin word fenestra to describe a window with glass, such as standard Swedish f?nster, or German Fenster. The use of window in English is probably due to the Scandinavian influence on the English language by means of loanwords during the Viking Age. In English the word fenester was used as a parallel until the mid-18th century and fenestration is still used to describe the arrangement of windows within a fa?ade.

　　From Websters 1828 Dictionary: Window, n.

　　History of window

　　Primitive windows were just holes in a wall. Later, windows were covered with animal hide, cloth, or wood. Shutters that could be opened and closed came next. Over time, windows were built that both protected the inhabitants from the elements and transmitted light: mullioned glass windows, which joined multiple small pieces of glass with leading, paper windows, flattened pieces of translucent animal horn, and plates of thinly sliced marble. The Romans were the first to use glass for windows. In Alexandria ca. 100 CE, cast glass windows, albeit with poor optical properties, began to appear. Mullioned glass windows were the windows of choice among European well-to-do, whereas paper windows were economical and widely used in ancient China, Korea and Japan. In England, glass became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century in Northern Britain. Modern-style floor-to-ceiling windows became possible only after the industrial glass making process was perfected.

　　Types of windows

　　Double-hung sash window

　　This sash window is the traditional style of window in the USA, and many other places that were formerly colonized by the UK, with two parts that overlap slightly and slide up and down inside the frame. The two parts are not necessarily the same size. Nowadays, 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. Double-hung sash windows were traditionally often fitted with shutters. Sash windows may be fitted with simplex hinges which allow the window to be locked into hinges on one side, while the rope on the other side is detached, allowing the window to be opened for escape or cleaning.

　　Single-hung sash window

　　One sash is movable and the other fixed. This is the earlier form of sliding sash window, and is also cheaper.

　　Horizontal sliding sash window

　　Has two or more sashes that overlap slightly but slide horizontally within the frame. In the UK, these are sometimes called Yorkshire sash windows, presumably because of their traditional use in that county.

　　Casement window

　　A window with a hinged sash that swings in or out like a door comprising either a side-hung, top-hung , or occasionally bottom-hung sash or a combination of these types, sometimes with fixed panels on one or more sides of the sash. In the USA, these are usually opened using a crank, but in parts of Europe they tend to use projection friction stays and espagnolette locking. Formerly, plain hinges were used with a casement stay. Handing applies to casement windows to determine direction of swing; a casement window may be left-handed, right-handed, or double. The casement window is the dominant type now found in the UK and parts of Europe.

　　Awning window

　　An awning window is a casement window that is hung horizontally, hinged on top, so that it swings outward like an awning.

　　Hopper window

　　A hopper window is a bottom hung casement window that opens similar to a draw bridge typically opening to the outside.

　　Tilt and slide window

　　A window where the sash tilts inwards at the top and then slides horizontally behind the fixed pane.

　　Tilt and turn window

　　A window which can either tilt inwards at the top, or can open inwards hinged at the side.

　　Transom window

　　A window above a door; in an exterior door the transom window is often fixed, in an interior door it can open either by hinges at top or bottom, or rotate on hinges. It provided ventilation before forced air heating and cooling. A fan-shaped transom is known as a fanlight, especially in the British Isles.

　　Jalousie window

　　Also known as a louvered window, the jalousie window consists of parallel slats of glass or acrylic that open and close like a Venetian blind, usually using a crank or a lever. They are used extensively in tropical architecture. A jalousie door is a door with a jalousie window.

　　Clerestory window

　　A window set in a roof structure or high in a wall, used for daylighting.

　　Skylight

　　A flat or slope window used for daylighting, built into a roof structure that is out of reach.

　　Roof window

　　A roof window at the Muse du Louvre A sloped window used for daylighting, built into a roof structure.

　　Roof lantern

　　A roof lantern is a multi-paned glass structure, resembling a small building, built on a roof for day or moon light. Sometimes includes an additional clerestory. May also be called a cupola.