An excellent resource for both students and researchers interested in mobile opportunistic networking. A well balanced mix of theoretical and practical aspects. Marco Conti, Institute of Informatics and Telematics (IIT), National Research Council of Italy (CNR), Italy I've been working on opportunistic networking since a friend was caught up in a disaster zone after a tsunami and couldn't use his smart phone, as the net was down, yet there were many devices around the town which had wireless and could store, carry, and forward messages, but no protocols to implement this useful service. This book covers in clear and up-to-date style, the principles and practice of the main communications mechanisms to date, and offers helpful exercises and useful information on how to implement these systems in practice. Jon Crowcroft, Fellow of IEEE, Fellow of ACM, Fellow of Royal Society (UK), University of Cambridge, UK