1 Introduction

3This is a book about how to design an internet. I say an internet rather than the Internet because the book is about not just the Internet we have today but also possible alternative conceptions of an internet—what we might instead have designed back then or might contemplate in the future. I take the word internet to describe a general-purpose, global interconnection of networks designed to facilitate communication among computers and among people using those computers. The book concerns itself with the implications of globality, the implications of generality, and the other requirements that such a network would have to meet, but it does not take the current Internet as a given—it tries to learn from the Internet of today, and from alternative proposals for what an internet might be, to draw some general conclusions and design principles about networks.