Window Screen

A window screen, insect screen or bug screen is a metal wire, fiberglass, or other synthetic fiber mesh, stretched in a frame of wood or metal, designed to cover the opening of an open window. Its primary purpose is to keep leaves, debris, insects, birds, and other animals from entering a building or a screened structure such as a porch, while permitting fresh air-flow. Most houses in Australia, the United States and Canada have screens on all operable windows, which are most useful in areas that have large mosquito populations. Formerly, screens in North America were usually replaced with glass storm windows in the winter, but now the two functions are usually combined in combination storm and screen windows, which allow glass and screen panels to slide up and down.