The term "Nearctic" refers to one of the eight biogeographic realms of the world, covering North America, including parts of Canada, the United States, and Mexico. This region is characterized by a diverse range of ecosystems, from tundra in the north to deserts in the south, supporting various flora and fauna. The Nearctic realm is home to many unique species, such as the American bison and the bald eagle. It also includes significant habitats like the Great Plains and the Appalachian Mountains, which contribute to its ecological diversity and importance in global biodiversity.