A bay window is a window

Window

A window is a transparent or translucent 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 float glass. Windows are held in place by frames, which...

 space projecting outward from the main wall

Wall

A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...

s of a building and forming a bay

Bay (architecture)

A bay is a unit of form in architecture. This unit is defined as the zone between the outer edges of an engaged column, pilaster, or post; or within a window frame, doorframe, or vertical 'bas relief' wall form.-Defining elements:...

 in a room, either square or polygonal in plan. The angles most commonly used on the inside corners of the bay are 90, 135 and 150 degree

Degree (angle)

A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...

s. Bay windows are often associated with Victorian architecture

Victorian architecture

The term Victorian architecture refers collectively to several architectural styles employed predominantly during the middle and late 19th century. The period that it indicates may slightly overlap the actual reign, 20 June 1837 – 22 January 1901, of Queen Victoria. This represents the British and...

. They first achieved widespread popularity in the 1870s.

The windows are commonly used to provide the illusion

Illusion

An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation. While illusions distort reality, they are generally shared by most people....

 of a larger room. They are used to increase the flow of natural light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 into a building as well as provide views of the outside that would be unavailable with an ordinary window.

External links

A San Francisco Chronicle

San Francisco Chronicle

thumb|right|upright|The Chronicle Building following the [[1906 San Francisco earthquake|1906 earthquake]] and fireThe San Francisco Chronicle is a newspaper serving primarily the San Francisco Bay Area of the U.S. state of California, but distributed throughout Northern and Central California,...

article discussing bay windows.