Window

This article is about the architectural element. For the computing term, see Window (computing). For the operating system, see Microsoft Windows.

A window is an opening in a wall or roof of a building, in a car etc., to let air and light in. It is usually filled with a sheet of glass. There can be many different shapes and sizes, including rectangular, square, circular, or irregular shapes. Some windows include coloured glass. Windows are usually transparent so that people can see through them.

A window of a house in England

Malaysian Prime Minister Mahathir Mohamad and U.S. Secretary of State Mike Pompeo are looking out the window together

Before glass was used in windows, people in Asia used paper to fill the hole in the wall. The paper would let light in.

Types of windows

There are different types of windows. They are:

Cross-window

A cross-window is one that has a vertical mullion and a horizontal transom, that make a cross.^[1]

Fixed window

A fixed window is one that cannot be opened. It is made to allow light to enter.^[2] The windows in churches are usually fixed.

Single-hung sash

A single-hung sash window is a window that has one horizontal sash at the bottom that can move up and down.^[1]

Double-hung sash

A double-hung sash is a window that has two sashes (panels) that can independently move up and down. One is usually the lower; one the upper.

Casement window

A casement window

A casement window is a window with a sash that has a hinge that swings in or out like a door. Casement windows are usually held open using a casement stay.

Skylight

A skylight

A skylight is a window built into a roof. This type of window allows natural daylight and moonlight to enter.

Roof lantern

The lantern over the dome of the Florence Baptistery

A roof lantern is a glass structure that has lots of different colours. It looks like a small building. It is built on a roof for day or moon light.^[3]

Stained-glass window

Sunlight shining through stained glass

A stained-glass window is a window that is made up of pieces of coloured glass. The coloured glass can be transparent, translucent or opaque. It usually shows people or places. Usually, the glass in these windows is separated by lead rods. Stained-glass windows are very common in churches.^[4]

How they are made

Different materials are used when making a window. For the frame of the window wood, polyvinyl chloride, composite, aluminium, steel, fiberglass are used.

Many windows have movable window coverings such as blinds or curtains. They keep out light and add insulation. They also ensure privacy. Windows allow natural light to enter. Too much can have bad effects such as glare and too much heat.^[5]