This Festschrift is dedicated to Ralf Steinmetz on the occasion of his retirement. The honoree is a full professor at the Technical University of Darmstadt in Germany, where he leads the Multimedia Communications lab. He has supervised over 105 successful PhD students and remains committed to his vision of achieving "seamless adaptive multimedia communications." He has been widely recognized for his contributions to the field, prestigious accolades include an Honorary Doctorate from RWTH Aachen University and a Chair of Excellence at the University Carlos III de Madrid. He is also a fellow of several esteemed professional organizations, including the IEEE, the ACM, the GI, and the VDE ITG. A pioneer in multimedia and networking, Ralf Steinmetz's work opened up further research in topics such as distributed systems, e-learning, and serious games. The contributions in this volume reflect his huge impact on research, technical developments, and careers in the areas of multimedia and networking: in Part I, the chapters discuss past research results and their impact, often applying a survey style; in Part II, researchers present current results; and in Part III, the chapters give an outlook on future research directions.