This document provides information about deserts. It defines a desert as an area that receives less than 250 mm of rainfall annually. It notes that during the day in deserts it can be 50°C while at night it can be -20°C. Most deserts are made of rocks and stones. It describes different types of deserts, including arid, semi-arid, cold, and coastal deserts. It also defines key terms like oasis and desertification.