Final answer:
Deserts cover 20% of the Earth's surface and occur in regions with limited rainfall. The four major types of deserts are hot and dry, semi-arid, coastal, and cold deserts.
Step-by-step explanation:
Deserts cover approximately 20% of the Earth's surface. They occur in regions where there is very limited rainfall, usually less than 250 millimeters per year. The four major types of deserts are hot and dry deserts, semi-arid deserts, coastal deserts, and cold deserts.
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