A biodiversity hotspot is a biogeographic region with a significant reservoir of biodiversity that is under threat from humans. Norman Myers wrote about the concept in two articles, revised after thorough analysis by Myers and others in 'Hotspots: Earth's Biologically Richest and Most Endangered Terrestrial Ecoregions'. To qualify as a biodiversity hotspot in Myers 2000 edition of the hotspot map, a region must meet two strict criteria: it must contain at least 0.5% or 1,500 species of vascular plants as endemics, and it has to have lost at least 70% of its primary vegetation. Around the world, 25 areas qualify under this definition.