The central idea of the World Heritage Convention is the "consideration that features of our cultural and natural heritage are of outstanding importance and therefore must be preserved as part of the common heritage of humanity”. The "outstanding universal value" means that these features have significance beyond national borders and are of importance to present-day as well as future generations. World Heritage Sites belong not only to the sovereign states in which they are found, but also to mankind’s global heritage.
Natural Heritage Sites represent unique natural phenomena, whereas cultural Heritage Sites preserve outstanding human achievements. Together, these unique natural landscapes, plant and animal habitats, geological formations, cultural landscapes and cultural treasures form the UNESCO World Heritage list. The most important criteria for admission to the World Heritage list are outstanding universal value, integrity and authenticity, as well as a commitment to protection and management.
Currently, there are 936 sites in 153 countries on the World Heritage list. Of these, 725 are cultural sites, 183 natural sites and 28 so called „mixed sites”, of both cultural and natural significance. There are 46 sites on the „List of World Heritage in Danger”, including the Rainforests in Madagascar and the Old City of Jerusalem and its Walls (as of September 2014).