Deserts can be hot or cold, but they are always dry. Around 1/5 of the Earth’s surface is covered in deserts. Deserts most commonly occur when there are unpredictable patterns of rainfall in an area, and the area usually has less than 30 cm of rain per year. In reaction to the extreme heat or the extreme cold, plants and animals make many adaptations. Plants have water-storing leaves or stems that reduce water loss and improve salt tolerance. Many animals learn to survive and get a lot of their moisture from these plants.
Deserts can also be fragile. There is a lot of slow-growing vegetation, and interference from vehicles disrupts the environment. Some tracts of vehicles from the past can still be seen in some areas today.