Douglas Comer is a professor at Purdue University where he teaches popular computer networking courses. He also
teaches hundreds of professionals and diverse audiences around the world each year about he Internet. He has written
a widely acclaimed and extremely popular series of books on networking and the Internet. He was one of the researchers
who contributed to the formation of the Internet in the late 1970s and 1980s. He has served on the Internet Architecture
Board, the group responsible for guiding development of the Internet, and is a Fellow of the ACM. He wrote this
book in response to everyone who has asked him for an explanation of the Internet that is both technically correct
and easily understood.
Preface
The Internet Book explains how computers communicate, what the Internet is, how the Internet works, and
what services the Internet offers you. It is designed for readers who do not have a strong technical background
� early chapters clearly explain the terminology and concepts needed to understand all the services. When you finish
reading, you will understand the technology behind the Internet, will appreciate how the Internet can be used,
and discover why people find it so exciting. In addition, you will understand the origins of the Internet and see
how rapidly it has grown.
Instead of using mathematics, algorithms, or computer programs, the book uses analogies from everyday life to
explain technology. For example, to explain why digital communication is superior to analog, the text uses an analogy
of sending signals through fog with a flashlight. To explain how audio can be played back for the user at a steady
rate when packets arrive in clumps, the text uses the analogy of many gallons of milk arriving at a supermarket
in one shipment, but being sold one gallon at a time.
In addition to explaining the services users encounter such as e-mail, file transfer, and web browsing, the
text covers key networking concepts such as packet switching, Local Area Networks, protocol software, and domain
names. More important, the text builds on fundamentals � it describes basic Internet communication facilities first,
and then shows how the basic facilities are used to provide a variety of services. Finally, the book includes an
extensive glossary of technical terms with easy-to-understand definitions; readers are encouraged to consult the
glossary as they read.
The third edition retains the same general structure as the previous edition, but adds four new chapters and
updates material throughout. Chapter 2 surveys a variety of Web sites, and encourages readers to begin exploring
the Web while they read. The other three new chapters are especially significant. Chapter 14 covers Internet connection
technologies, including ADSL and cable modems, technologies which are now available to consumers. Chapters 29 and
30 cover the related topics of security and ecommerce, both of which are increasingly important. Chapter 29 explains
encryption technology, and Chapter 30 shows how the technology is used to conduct business.
As with the previous edition, the book is divided into four main parts. The first part begins with fundamental
concepts such as digital and analog communication. It also introduces packet switching, and explains the Local
Area Network technologies that are used in most businesses.
The second part of the book gives a short history of the Internet research project and the development of the
Internet. Although most of the history can be skipped, readers should pay attention to the phenomenal growth rate,
which demonstrates that the technology was designed incredibly well � no other communication technology has remained
as unchanged through such rapid growth.
The third part of the book explains how the Internet works, including a description of the two fundamental protocols
used by all services: the Internet Protocol (IP) and the Transmission Control Protocol (TCP). Although they omit
technical details, the chapters in this part allow students to understand the essential role of each protocol and
gain perspective on the overall design.
The fourth part of the book examines services available on the Internet. In addition to covering browsers, plugins,
CGI, and search engines used with the World Wide Web, chapters discuss e-mail, network newsgroups, file and fax
transfer, and audio and video communication. In each case, the text explains how the service operates and how it
uses facilities in the underlying system.
The Internet Book makes an excellent reference text for a college-level course on the Internet. Although
presented in a nontechnical manner, the material is scientifically accurate. More important, in the twenty-first
century, an educated person will need to know more than how to use a browser or set up a Web page � they should
have some understanding of what goes on behind the scenes. They can acquire such knowledge from this text.
Instructors are encouraged to combine classroom lectures with laboratory sessions in which students see and
use the technology first-hand. In all courses, early labs should focus on exploring a variety of services, including
sending e-mail, using a browser, using a search engine, downloading files via FTP, listening to audio, and using
an IP telephone, if one is available. I encourage all students, even those who have no interest in computers, to
build a trivial Web page by hand. In addition to helping them see the relationship between tags in an HTML document
and the resulting display, it shows students how a server transfers files on a computer disk to a browser. Seeing
the relationship in labs helps students better understand as they read about the underlying process.
Lab projects later in the semester depend on the type of course. Business-oriented courses often focus students
on using the Internet � labs require students to search the Internet for information and then use the information
to write a short paper. Other courses use labs to focus on tools such as programs used to create a Web page. Some
courses combine both by having students search for information and then create a Web page that contains links to
the information. In any case, we have found that students enter Internet courses with genuine enthusiasm and motivation;
a professor's task is merely to provide perspective and remind students throughout the semester why the Internet
is so exciting.
The author thanks many people who have contributed to editions of this book. John Lin, Keith Rovell, Rob Slade,
and Christoph Schuba read early versions and made suggestions. Dwight Barnette, George Polyzo, Donald Knudson,
Dale Musser, and Dennis Ray sent the publisher reviews of a previous edition. Scott Comer provided a student perspective.
As always, my wife, Chris, carefully edited the manuscript, solved many problems, and improved the wording.
Douglas E. Comer
March, 2000
Summary
The INTERNET Book:
Provides an overview of Electronic Commerce and how the Internet can be used to conduct business and commercial
transactions.
Includes Security and Encryption with respect to Internet commerce, why security is needed, and the technologies
that provide secure communications.
Describes getting started with hands on experience with the concept of a Web browser and examples of Web sites
to visit.
Updates topics throughout and adds information about current technologies such as shopping carts, cookies,
personalized Web search results, Internet faxes, remote desktops, and streaming audio and video.
Covers Internet connection technologies: ADSL, cable modems, and wireless networks.
Table of Contents
1. The Internet Has Arrived.
2. Getting Started: Hands-On Experience.
I. INTRODUCTION TO NETWORKING.
3. Telephones Everywhere.
4. The World Was Once Analog.
5. The Once and Future Digital Network.
6. Basic Communication.
7. The Local Area Network Arrives.
II. A BRIEF HISTORY OF THE INTERNET.
8. Internet: The Early Years.
9. Two Decades of Incredible Growth.
10. The Global Internet.
11. A Global Information Infrastructure.
III. HOW THE INTERNET WORKS.
12. Packet Switching.
13. Internet: A Network of Networks.
14. ISPs and Network Connections.
15. IP: Software to Create a Virtual Network.
16. TCP: Software for Reliable Communication.
17. Clients + Servers = Distributed Computing.
18. Names for Computers.
19. Why the Internet Works Well.
IV. SERVICES AVAILABLE ON THE INTERNET.
20. Electronic Mail.
21. Bulletin Board Service (Network News).
22. Browsing the World Wide Web.
23. World Wide Web Documents (HTML).
24. Advanced Web Technologies (Forms, Frames, Plugins, CGI, Java, JavaScript).
25. Automated Web Search (Search Engines).
26. Audio and Video Communication.
27. Faxes and Files (FTP).
28. Remote Login And Remote Desktops (TELNET).
29. Facilities for Secure Communication.
30. Electronic Commerce and Business.
31. The Global Digital Library.
