Original: A team of biologists convened by the World Wildlife Fund (WWF) developed a system of eight biogeographic realms (ecozones) as part of their delineation of the world's over 800 terrestrial ecoregions.
Simplified: A team of biologists convened by the World Wide Fund for Nature (WWF) developed a system of eight biogeographic realms (ecozones) as part of their delineation of the worlds over 800 terrestrial ecoregions.