Louvres, which are shutters or blinds with angled horizontal slats, are nowadays mainly placed for their decorative appeal. In the past louvre systems were often made out of wood, even today wood is still used to build some louvre systems. But most modern louvres are built using modern materials like aluminium, metal, glass, copper, stainless steel or titanium. Sometimes louvre systems are also used in the construction of front doors or on closets as decoration. Louvre systems can even be constructed into a ceiling. However, the main reasons for using louvre systems is still ventilation, sun shading, sun control or decorative purposes.