Here are some sure things: you can't get a virus by simply reading an email. Malicious code can't harm hardware. A virus can't hide from a booted, write-protected diskette. Your computer can't get infected from a picture file. I have given this advice hundreds of times and could repeat it in my sleep. It was the mantra of every antivirus researcher. We had to repeat it to every inquiring emailer asking if today's computer virus hoax was something to be afraid of. There was only one problem. We were wrong! Well, we weren't wrong at the time. Then the Internet became everything. Computers advanced. New computer languages were created. Old languages were expanded. Writing programs became easier and so did writing malicious code to do bad things. Write it once today and spread it to 60 million computers tomorrow.

Worms, like Melissa and I Love You, routinely shut down tens of thousands of networks in hours. The CIH virus erased the hard drives and corrupted the ROM BIOS chips of over ten thousand computers in a single day. You can unwittingly click on a hacker web site that later on records your credit card and bank account information when you log onto your bank's "secure" web site. Simply joining an instant messaging conversation can allow complete access to your home system. When browsing the Internet, your browser will automatically download and run programs. A rogue program can harm your system and all you did was surf the Web. Today, more than ever, malicious mobile code can hurt your system.

There are over fifty thousand different computer viruses, Trojan horses, and malicious Internet programs. Hundreds of web sites and dozens of international hacker clubs are dedicated solely to silently invading your computer system. They have contests with prizes to see who can write the most wicked creation. There is a lot of collective personal effort directed toward destroying your privacy and data. If your job involves computers, malicious programs can be more than an inconvenience. This book will help you protect your Microsoft Windows system and networks.