Human Design: The Definitive Book of Human Design, The Science of Differentiation by Ra Uru Hu

This is one of the most essential Human Design books, written by Ra Uru Hu—the founder of the system. It offers a clear and structured introduction to the core mechanics of Human Design, including Type, Strategy, Authority, and the deeper science behind it all. While there are free resources online, this book is a powerful place to begin if you're ready to explore the system with depth and integrity—direct from the source.