A window is an opening in a wall, door or roof that allows the passage of light and, if not closed or sealed, air and sound
Modern windows are usually glazed or covered in some other transparent or translucent material. Windows are held in place by frames. 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.
A bay window is a window space projecting outward from the main walls of a building and forming a bay in a room. Bay window is a generic term for all protruding window constructions, regardless of height. The most common inside angles are 90, 135 and 150 degrees, though triangular bays formed of two windows set at 120 degrees may be found. Most are polygonal or square; when curved they are called bow windows. A bay window with a flat front and angled sides is called canted. A bay window supported by a corbel, bracket or similar it is called an oriel window.
A casement window is a window that is attached to its frame by more than one hinge. Casement windows are hinged at the side. Windows hinged at the top are referred to as awning windows. Ones hinged at the bottom are called hoppers. They are used singly or in pairs within a common frame, in which case they are hinged on the outside. Casement windows are often held open using a casement stay.
A sliding window is basically made up of horizontal sashes that move sideways with the help of rollers at the bottom of the sashes. They can span from the floor to the ceiling, span entire walls or even come in the dimensions of a regular small window.