The Changing World of Mobile Communications: 5G, 6G and the Future of Digital Services," is a new open-access book that offers a panoramic view of the future of mobile communications. Edited by Petri Ahokangas and Annabeth Aagaard and drawing on international expertise, the book presents a multi-disciplinary exploration into the technical, business, and regulatory landscapes shaping the transition from 5G to the visionary 6G. It encapsulates the collective wisdom of researchers from the University of Oulu's 6G Flagship, alongside global academics, providing insights into how these technologies will redefine digital services, business models, and societal norms. This book is poised to be an indispensable resource for anyone invested in the future of mobile communications and digital innovation.