Argon Gas- This odorless, colorless gas is inserted between panes of glass for insulation and also increases a window's energy efficiency by reducing conductive heat transfer.

Awning Window- This style of window swings out from the bottom and away from a building, just like an awning.

Bay Window- A three-unit window with a center piece flanked by two side panels that are usually angled at 30 or 45 degrees.

Bow Window- A combination of windows composed of four or more units, which are aligned in a smooth curving contour.

Casement Window- A window that swings open from the side, hinging at the top and bottom of the frame. Nailing Fin (Flange)- A strip of sheet material either integral or fastened to a unit's frame, creating a flange. This is a common method to install new construction windows and doors.

Double Hung Window- Consists of top and bottom vertically sliding sashes in a single frame. Picture Window- A large, fixed or stationary window designed to provide a maximum viewing area without obstructions.

Emissivity- The relative ability of a surface to radiate heat. R Value- Measure of a window's overall resistance to heat transmission from different air temperatures on either side of the glass.

Frame- The outer components of a window or door unit, consisting of a head jamb, side jambs, blind stops and window sills, as applies. Sash- A wood/vinyl perimeter to support the glass of a window, holding it separately from the frame and allowing some independent movement from the frame.

Fusion Welded- A process of melting two or more items together (i.e., a window sash and frame) via welding. Single Hung Window- A window system with only one glass unit movable in the window pane.

Geometric Window- Specialty windows customized to fit a variety of shapes, such as starburst, gothic, colonial, etc. within a door pattern.

Glazing- 1) Act of fitting a window or door frame with glass. 2) Installing glass into a window or door frame. Slider Window- A window that opens horizontally.

Glazing Bead- A long, thin piece of moulded wood used to secure glass to the sash or frame of a window; silicone is often used to create a seal between the glass and wooden glazing bead.

Hermetically Sealed- An airtight seal.

Insulating Glass- Comprised of two or more pieces of glazing (glass) separated by hermetically sealed airspace for improved thermal efficiency.

Kickplate- Applied to one or both sides of a door's bottom rail, this thin, polished metal plate is used to prevent denting and soiling of the wood surface.

Laminating- Method of bonding two or more layers of glass together using heat and pressure, with inner layers of transparent plastic. This process provides one of the best avenues to blocking ultraviolet rays.

Low E Glass- Windows that have been coated with a transparent, metallic layer to the glass surface, reducing its emissivity or ability to radiate heat.

Mulled- To join two windows or doors together, side by side.

NCTL Validated- National Certified Testing Labs (NCTL) is an organization that performs standardized tests on windows to ensure proper quality control levels.

NFRC Rating- The National Fenestration Rating Council (NFRC) is a non-profit group comprised of manufacturers, builders, designers, government officials, utilities and consumers working together to provide unbiased energy performance ratings for windows, doors and skylights (fenestrations).

Tempered Glass- Plate glass with increased strength due to a special heat-treatment for greater strength as a safety glass.

Thermal Performance- A window's ability to act as a barrier to the transfer of heat.

Thermo-Edge Spacer- A system where protected insulated glass creates increased temperatures along the window's edges and therefore reduces the potential for condensation on the glass surface.

Transom- An operating window unit for specific use above a door or window.

Weatherstripping- Material used to provide a weather-tight seal between a window/door sash or frame.