*From Wikipedia, the free encyclopedia http://en.wikipedia.org/wiki/Window_shutter

A window shutter panel is a solid window covering usually consisting of side stiles, top and bottom rails, and louvers. Individual shutter panels can be hinged together to form a shutter unit, which fills a window opening. The term window shutter includes both interior shutters, used on the inside of a house or building, and exterior shutters, used on the outside of a structure. Shutters are used to control sunlight, provide privacy, add protection from weather, and architectural allure.

Interior shutters are semi-opaque window coverings that block almost all light when closed. Shutters usually hinge on either side of a window opening, and swing open to allow access to the window or for light to enter the room. Standard panels have movable louvers that rotate open for light and visibility and rotate closed for privacy or to reduce light. Styles available include traditional, or colonial, shutters that use 1-1/4 inch louvers, and plantation shutters that use wider louvers. Some interior shutters use stationary louvers that do not move, solid raised panels, fabric inserts, or tinted glass. Shutters can be configured in a single tier unit that used one panel from top to bottom of a window opening. Double tier units use two panels from top to bottom, which allows the top panels to be opened independent from the bottom panels. CafÈ type shutters only cover the lower portion of a window. A horizontal divider rail may be used to create a top and bottom louver section in a single panel. A tilt bar (rod) is used for adjusting the louver position and to keep louvers in a uniform position. Interior shutters can be constructed from numerous woods, which can be painted or stained, aluminums and a variety of synthetic materials. Interior shutters that are made to close tolerances are preferable for the best possible fit. When louvers or tilt bar (rod) become damaged, replacement kits for these damaged parts may be ordered online and are easy to install.

Exterior shutters were originally constructed for light control, privacy, and protection from the elements. Function shutters hinge to either side of a window, and swing closed when necessary. Fixed louvers shed rain, allow air transfer, filter direct sunlight, protect from small flying debris, and provide privacy. Multi-functional shutters use movable louvers that allows for greater control. Solid panels are generally used for protection during severe weather. Most other styles, such as board-and-batten, are used in non-functional situations and are specifically to enhance the features of a building. Functional shutters are constructed from solid woods that have proven to endure outside elements ( e.g. red cedar). Finishing wood shutters is recommended for extended life. Non-functional exterior shutters can be constructed from vinyl or other synthetic materials. Non-functional shutters simply screw or bolt directly to the building.