A desert is any place that gets very little rain, usually less than 25 centimetres in a whole year. Most people picture burning sand and blazing sun, and many deserts are like that. But the largest desert on Earth is not hot at all. It is Antarctica, a frozen land where almost no rain or snow ever falls.

Living with so little water is hard, so desert plants and animals have clever tricks. A cactus stores water in its thick stem and has sharp spines instead of leaves, which lose far less water than broad leaves would. Many desert animals hide in cool burrows during the day and come out to hunt at night, when the air is cooler.

Camels are famous desert travellers. People once believed their humps were full of water, but this is a myth. The humps store fat, which the camel uses for energy when food is scarce. A camel can also drink a huge amount of water very quickly, then go for days without another drink.