For over 300 million years reptiles have walked, flown, and slithered over the face of our Earth. From dinosaurs to living reptiles such as lizards, snakes, crocodiles, and turtles, reptiles have come in all shapes and sizes. This Very Short Introduction discusses the adaptations that first enabled reptiles to leave the water, such as their waterproof skin, and eggs which can survive on dry land. Considering the many different living groups of reptiles today, Kemp describes how their respective bodies are adapted for their different ways of life, from snake feeding patterns to the way crocodiles breathe, and assesses the threat of extinction many reptile species face.