The programme catalogues, names, and conserves sites of outstanding cultural or natural importance to the common culture and heritage of humanity. The programme began with the Convention Concerning the Protection of the World Cultural and Natural Heritage,[10] which was adopted by the General Conference of UNESCO on 16 November 1972. Since then, 195 states have ratified the convention,[11] making it one of the most widely recognised international agreements and the world's most popular cultural programme.[12] To be considered, the properties must be under some form of state protection or conservation and be nominated by the host member country.