Introduction

In the course of cruising the World Wide Web and clicking a link, have you ever wondered, "How does that work?" Or perhaps this question popped into your mind while you were transferring a file to your computer via FTP, or reading a newsgroup message, or when you first heard about technologies such as spam, cookies, and firewalls. Maybe you've wondered how a message sent from your computer travels through the vastness of cyberspace and ends up in the right email box halfway across the world. Have you ever wanted to know how search tools find the exact piece of information you want out of the millions of pieces of information on the whole Internet? How can you listen to music and view animations while surfing the Web?

This book is designed for everyone interested in the Internet. Its guiding principle is this: No matter how much of a cyberpro you areor how much of a novicethere's a lot you don't understand about the Internet. Here's just one small example. I have a friend who has made his living with companies involved with the Internet for many years. He's a complete cyberpro who lives and breathes the Internet. One day, he almost whispered to me, "I don't like to admit this, but I don't know what a proxy server is. How does it work, anyway?"

He's not alone. The Internet changes so quickly and the technology advances so rapidly that it can seem almost impossible to keep up with all of it. If you're like just about everyone else involved in the Internet, your questions are similar to those of my friend. You'll find your answers here.

In Part 1, "Understanding the Internet's Underlying Architecture," I explain the underlying basics of the Internet: who runs it, how TCP/IP works, how to understand Internet addresses and domains, and similar topics. Here's where you'll find out about things such as routers and how the client/server architecture underpins virtually every aspect of the Internet.

Part 2, "Connecting to the Internet," depicts the various ways you can connect your computer to the Internet. There are myriad ways you can connect, such as via a cable modem, a digital subscriber line (DSL), an online service, a satellite, wirelessly, and many other ways. We'll cover all that, and more, in this section.

Part 3, "Communicating on the Internet," covers every aspect of Internet communications. It shows how email and newsgroups work, how IRC chat works, what email "spam" is and what you can do to prevent it, how instant messaging works, and how you can use the Internet and a technique called VoIP to make telephone calls anywhere in the world. And it also shows you how blogging works, which has become an increasingly important part of our culture.

Part 4, "How the World Wide Web Works," covers what has become by far the most popular part of the Internetthe World Wide Web. You'll learn virtually every aspect of how the Web works. It delves into how browsers work, how web server software works, and how Hypertext Markup Language (HTML) works. This section also covers the ways in which the Web is becoming integrated directly into your computer, how web pages are published and organized on a site, and every other aspect of the Web that is likely to be of interest to you. It also explains many of the newest web technologies, which will become even more important in the future, notable web services, and grid computing.

Part 5, "Using the World Wide Web," shows you the Web in actual real-world use. So you'll find out how Google is able to search the entire Internet and find exactly what you're looking for, and how map sites can give you driving locations anywhere you want to go. It also takes you behind the scenes of Wikipedia, a free, online encyclopedia put together entirely by thousands of volunteers.

Part 6, "Using Common Internet Tools," takes a close look at common Internet tools. Here's the place to learn about basic tools and services, such as telnet, and what happens when you use FTP to download a file to your computer. It's the section of the book that covers cutting-edge Internet technology. You'll find out how Java and ActiveX programming languages work, how JavaScript works, how agents can silently do your bidding for you, and how the Common Gateway Interface (CGI) works, which is a little-known but vital part of the Internet.

Part 7, "Enjoying Entertainment and Multimedia on the Internet," shows you how some of the most exciting parts of the Internet workthe various multimedia technologies. Whether you want to know how virtual reality or animations work, how streaming video works, how videoconferencing works, or how similar technologies work, you'll find it all here. And it also shows you how the iPod works, along with iTunes and podcasting.

Part 8, "Shopping and Doing Business on the Internet," covers intranets, how the Internet works with the outside world, and how you can shop online. You'll see how companies use Internet technologies to build their own private networks, called intranets. And you'll take a close look at the underlying technologies that let you shop on the Web, which accounts for billions of dollars a year in sales.

Finally, Part 9, "Protecting Yourself on the Internet," covers security concerns. The chapters in this part explain the controversial cookie technology that lets web servers put bits of information on your hard disk and use that information to track you, how the even-more controversial FBI system called Carnivore wiretapped people's use of the Internet to read their email, watch their web browsing, and more. They also look at the National Security Agency's Echelon program, which allows for web snooping and wiretapping on a global scale.

This part also shows how firewalls work, how viruses can attack your computer, and how cryptosystems allow confidential information to be sent across the Internet. It delves into how hackers can attack Internet service providers (ISPs) using so-called Denial of Service or "smurf attacks," and how they can attack your computer as well. This section also looks at how "spyware" can report on your surfing activities, and how your place of employment may monitor your Internet activities. And it covers the issue of pornography on the Internet and shows how parental-control software can prevent children from seeing objectionable material.

So, come along and see how the vast Internet works. Even if you're a cyberpro (and especially if you're not), you'll find out a lot you never knew.