The concept of ‘biological diversity’ is multifaceted and complex. It includes the concept of species diversity, or the total of all species in a given area or habitat, but can also refer to genetic diversity within a species. Biodiversity can even refer to the diversity of habitats in a given region. Biodiversity is important as it reflects the environmental health of a species, region, or habitat. On a global scale, biodiversity is being lost at an alarming rate, largely due to habitat destruction. In this section there are models that explore biodiversity equilibrium, and provide data for various estimates of biodiversity.