The ten largest deserts by surface area

Deserts take up about one third of the Earth's land surface.[11] Bottomlands may be salt-covered flats. Eolian processes are major factors in shaping desert landscapes. Polar deserts (also seen as "cold deserts") have similar features, except the main form of precipitation is snow rather than rain. Antarctica is the world's largest cold desert (composed of about 98% thick continental ice sheet and 2% barren rock). Some of the barren rock is to be found in the so-called Dry Valleys of Antarctica that almost never get snow, which can have ice-encrusted saline lakes that suggest evaporation far greater than the rare snowfall due to the strong katabatic winds that even evaporate ice.

Reference 1: Area (km²) and Area (mi²).

Reference 2: Antarctic Desert (Antarctica), Arctic Desert (Arctic), Sahara Desert (Africa), Arabian Desert (Middle East), Gobi Desert (Asia), Patagonian Desert (South America), Great Victoria Desert (Australia), Kalahari Desert (Africa), Great Basin Desert (North America) and Syrian Desert (Middle East).

Source: http://en.wikipedia.org/wiki/Deserts