Oribatid mites have successfully invaded almost all compartments of the biosphere. They are ubiquitous and, with the exception of the open oceans, they exist in every sort of terrestrial, aquatic, arboreal and parasitic habitat. They are found at every elevation and every latitude, from the Arctic to the Antarctic. Mites have a diversity of function in the ecosystem, as shown by the range of feeding guilds to which they belong. They include predators, parasites, fungal feeders, root feeders, bacterial feeders, omnivores, and scavengers. Ignoring mites, however, is a mistake. They are not passive inhabitants of ecosystems; rather they are strong interactors and major components of biological diversity.