Leadership in Energy and Environmental Design (LEED) is a certification program for the design, construction and operation of high performance green buildings since 2002. This mark of excellence is known across the world and there are four levels of excellence. There are 100 possible base points distributed across five major credit categories: Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, plus an additional six points for Innovation in Design and an additional four points for Regional Priority. Buildings can qualify for four levels of certification.