What is the Internet? Most of us perceive it as a big, single, seamless structure -- when it's actually a set of largely autonomous, loosely coordinated communications networks. This timely book explains basic design choices that underlie the Internet's success; identifies key trends in the evolution of the Internet; evaluates current and prospective technical, operational, and management challenges; and explores the resulting implications for decision makers. It's helpful to anyone looking for direction as the Internet continues to take shape.