Humanity was nomadic for 99% of its existence. Sedentary life, national borders and the creation of identity documents for increasingly stricter population control are comparatively recent phenomena, and paradoxical given that the world is becoming ever more globalized. The recent emergence of populist movements in the West that are focused on closing borders and rejecting others raises serious questions about our sense of fraternity, especially when we could be facing ever larger migration movements due to the climate crisis. This book concisely explains what migration is, its causes and consequences, and the humanistic and legal aspects regarding it in the simplest, most objective ways possible, so that children have all the information they need to understand the world around them.