Any barren region that supports very little life may be called a desert. The cold expanses of Antarctica, extreme northern Asia, and Greenland are therefore true, but cold, deserts. Most commonly, however, the term desert is used for regions that are barren because they are arid, or dry. Arid deserts receive little precipitation and are characterized by specialized plants that tolerate drought conditions and salty soils, and by distinctive land features. Most desert areas get less than 5 inches (13 centimeters) of rain in a year. The rainfall ....