Desert biomes are characterized by very little moisture. These dry lands receive less than 40 centimeters of precipitation in a year compared to over 100 centimeters in the rainforest.
Deserts can be either hot or cold.
The important thing to remember is that deserts are dry. Deserts can be found in tropical regions where there is little rainfall. Other deserts can form where mountains receive most of the rain. This is called the rain shadow. The great Gobi Desert of Mongolia has little rainfall because the Himalaya Mountains to the south prevent rainfall from moving to this region.