In geography desert is defined as the land area in which rainfall rarely exceeds 250 mm per year and the land is arid.The desert can be considered an ecosystem or biome.A desert is a biome that receives little rainfall. They have a reputation of having little life, but that depends on the kind of desert, in many there is abundant life, the vegetation is adapted to the low humidity and animals usually hide during the day to preserve moisture. The establishment of social groups in the deserts is complicated and requires a significant adaptation to the extreme conditions prevailing in them. Deserts make up the largest area of the earth's surface more than 50 million square kilometers, occupying nearly a third of it. Of this total, 53% are hot deserts and cold deserts 47%.
Erosion processes are important factors in the formation of desert landscape. Depending on the type and degree of erosion that wind and solar radiation have caused, the deserts have different types of soil: sandy desert is that they are composed primarily of sand, which by the action of the wind shapes the dunes, stony or rocky desert is one whose land is made up of rocks or pebbles (this type of desert is often referred to the Arabic word hamada).
The deserts may contain valuable mineral deposits that were formed in the arid environment, or were exposed by erosion. In the lower zones may form salt flats. Due to the dry deserts are ideal places for the preservation of human artifacts and fossils.
It also defines wilderness as an uninhabited place, not inhabited by humans or barely living at all. By this definition, the deserts are also located in colder climates such as the Arctic or tundra.
Patagonia desert 
