What makes a national park?

A national park is a reserve of land, usually owned by a national government, protected from most human development and pollution. National parks are a protected area of IUCN category II. The largest national park in the world is the Northeast Greenland National Park, which was established in 1974. The number of areas managed by the National Park Service in the United States of America consists of over 400 different sites, of which 58 carry the designation of National Park.