Deserts are areas that receive very little precipitation. People often use the adjectives “hot,” “dry,” and “empty” to describe deserts, but these words do not tell the whole story. Although some deserts are very hot, with daytime temperatures as high as 54°C (130°F), other deserts have cold winters or are cold year-round. And most deserts, far from being empty and lifeless, are home to a variety of plants, animals, and other organisms. People have adapted to life in the desert for thousands of years.
One thing all deserts have in common is that they are arid, or dry. Most experts agree that a desert is an area of land that receives no more than 25 centimeters (10 inches) of precipitation a year. The amount of evaporation in a desert often greatly exceeds the annual rainfall. In all deserts, there is little water available for plants and other organisms.
Deserts are found on every continent and cover about one-fifth of Earth’s land area. They are home to around 1 billion people—one-sixth of the Earth’s population.
Although the word “desert” may bring to mind a sea of shifting sand, dunes cover only about 10 percent of the world’s deserts. Some deserts are mountainous. Others are dry expanses of rock, sand, or salt flats.
