Arid deserts are regions characterized by extremely low rainfall, typically receiving less than 10 inches (25 cm) of precipitation annually. These areas often have high temperatures during the day and cooler temperatures at night. The lack of moisture leads to sparse vegetation, with plants like cacti and succulents adapted to survive in harsh conditions. The soil in arid deserts is usually sandy or rocky, making it difficult for most plants to grow. Despite the challenging environment, some animals, such as camels and lizards, have evolved unique adaptations to thrive in these dry habitats. Arid deserts cover about one-third of the Earth's land surface.