A louver is a specific type of shutter, blind or window which is characterized as having a specific kind of slatted opening. Louvers are as much practical as they are aesthetic, since the slats are designed chiefly to keep unwanted elements out of the home.
The most notable feature of a louver are its slats. A louver has horizontal or vertical slats that are designed to maximize the amount of air and sunlight that may enter into its adjoining room. However, the angle of the slats are constructed so that rain, direct sunlight and noise can be minimized and kept out of the adjoining room. Slat angles can usually be adjusted in blinds or windows but they can also be permanently fixed into a predetermined position.
The origin of the louver can be traced back to Middle Ages. Louvers started as makeshift constructions that were built into holes found in kitchen roofs. They were usually composed of scrap material like from a barrel. People constructed louvers to simultaneously block unwanted rain and snow and allow for kitchen ventilation. As the popularity of the louver grew, construction methods became more intricate. Pottery constructions with designs mimicking the human face caught on and some louvers in the Middle Ages were created so that smoke and other debris could leave through the designs' eyes or mouths.
Louvers in the Middle Ages that weren't fixed could be opened or closed using a string that was connected to the structure. Dwellers could pull on the string each time adjustments to slat angles needed to be made. In the same way, modern louvers may be open and shut using levers or another similar mechanism. Metal levers can be commonly found on louvers that are composed of glass or another delicate material. Typically, however, the modern louver is composed of vinyl or, like the original louvers, of wood.
While louvers are generally thought to be part of a window, other uses for them exist. Louvers can be added to a closet or dressing room door to increase privacy. They can also be constructed to help with a home's heating and air conditioning ventilation system. Though louvers are still in use today, modern architects are more apt to use them as a technical device rather than a primary one. Some architects purposefully use the louver to accent or add an extra aesthetic element to an otherwise practical design.