This book focuses on the first vertebrates to conquer land and their long journey to become fully independent from the water. It traces the origin of tetrapod features and tries to explain how and why they transformed into organs that permit life on land. Although the major frame of the topic lies in the past 370 million years and necessarily deals with many fossils, it is far from restricted to paleontology. The aim is to achieve a comprehensive picture of amphibian evolution. It focuses on major questions in current paleobiology: how diverse were the early tetrapods? In which environments did they live, and how did they come to be preserved? What do we know about the soft body of extinct amphibians, and what does that tell us about the evolution of crucial organs during the transition to