By starting at the application-layer and working down to the protocol stack, this text provides a motivational treatment of important concepts for networking students. Based on the rationale that once a student understands the applications of networks they can understand the network services needed to support these applications, this book takes a "top-down" approach, where students are first exposed to a concrete application and then drawn into some of the deeper issues of networking. This book focuses on the Internet as opposed to addressing it as just one of many computer network technologies. Computer networking has become synonymous with the Internet, and most computer networking students have had significant experience using the Internet. They are enormously curious about what is "under the hood" of the Internet, creating an extremely motivational vehicle for teaching fundamental computer networking concepts. This book features a comprehensive companion website which allows for direct access to some of the best Internet sites relating to computer networks and Internet protocols.