Deserts

A desert is a barren area of land where little precipitation occurs and consequently living conditions are hostile for plant and animal life. 

The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. 

(In geology, denudation is the long-term sum of processes that cause the wearing away of the earth’s surface leading to a reduction in elevation and relief of landforms and landscapes. 

Endogenetic processes such as volcanoes, earthquakes, and plate tectonics uplift and expose continental crust to the exogenetic denudation processes of weathering, erosion, and mass wasting.)

About one third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.

Major deserts:-

• The Sahara is the largest subtropical hot desert and third largest desert after Antarctica and the Arctic. At over 9,400,000 square kilometers (3,600,000 sq mi), it covers most of North Africa.
• The Gobi is a large desert region in Asia. It covers parts of northern and northwestern China, and of southern Mongolia. The desert basins of the Gobi are bounded by the Altai Mountains and the grasslands and steppes of Mongolia on the north, by the Hexi Corridor and Tibetan Plateau to the southwest, and by the North China Plain to the southeast. The Gobi is most notable in history as part of the great Mongol Empire, and as the location of several important cities along the Silk Road.
• The Kalahari Desert  is a large semi-arid sandy savannah in southern Africa extending 900,000 square kilometres (350,000 sq mi), covering much of Botswana and parts of Namibia and South Africa. A semi-desert, with huge tracts of excellent grazing after good rains, the Kalahari supports more animals and plants than a true desert, such as the Namib Desert to the west.
• The Patagonian Desert, also known as the Patagonia Desert or the Patagonian Steppe, is the largest desert in Argentina and is the 7th largest desert in the world by area, occupying 673,000 square kilometers (260,000 mi²). It is located primarily in Argentina with small parts in Chile and is bounded by the Andes, to its west, and the Atlantic Ocean to its east, in the region of Patagonia, southern Argentina. 
• The Arabian Desert is located in Western Asia. It is a vast desert wilderness stretching from Yemen to the Persian Gulf and Oman to Jordan and Iraq. It occupies most of the Arabian Peninsula, with an area of 2,330,000 square kilometers (900,000 sq mi). At its center is the Rub'al-Khali, one of the largest continuous bodies of sand in the world.
• The Great Victoria Desert, an interim Australian bio region, is a sparsely populated desert area in Western Australia and South Australia.
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• The Great Basin Desert is the largest US desert North America and covers 190,000 square miles (490,000 km²).