II. Is Spyware a Virus?

At this point, you might still be thinking that your computer is sufficiently protected against spyware infections and that you don't have anything to worry about. After all, you bought the newest anti-virus software from your computer store and paid the fee they charged you to receive automatic updates for the next year. So, you should be safe from everything, right?

Unfortunately that's not quite the case. Like I said earlier in this section, although viruses and spyware both fall under the heading of "malicious software," they're not quite the same thing. How are they different? In technical terms, a virus is a small piece of computer code a miniature computer program, in other words that attempts to spread from one computer to another through email attachments or over the Internet. Viruses range from annoying to destructive in nature: the miniature computer program can do anything from just clogging up your Inbox with unwanted emails all the way to modifying or deleting important files on your hard drive.

Spyware, on the other hand, is only "spread" by someone installing a piece of software that has spyware piggy-backing on top of it, or by browsing to a website that installs it automatically. So the largest difference between spyware and viruses is that, for the most part, spyware does not attempt to spread itself to other computers in the same way that a virus does.

But now we should move past the technical distinctions and talk about the more important question: "Why do I care that viruses and spyware are different?" And the answer to that question is quite simple, and a little frightening:

Most (if not all) anti-virus software is not able to protect you against spyware.

Anti-virus software does a great job at finding and removing viruses, especially if you keep your anti-virus definitions up-to-date. But anti-virus software by itself will do next to nothing to detect or prevent spyware infections. This is because anti-virus software scans for the particular piece of code that makes up a virus and uses that signature to prevent the virus from causing any damage to your computer. But for the most part, anti-virus software doesn't detect spyware because spyware doesn't have the same sort of easily-identifiable signature as a virus. As time has gone on, some newer versions of virus scanners have begun to incorporate spyware scanning capabilities. But not everyone's doing it, and the ones that are doing it still have quite a way to go. I can't tell you the number of times I've run a virus scan on somebody's home PC and had it come back clean, only to run a spyware detection tool and find dozens or hundreds of spyware applications installed on their computer. In order to fully protect your PC from the malicious software that exists on the Internet, you need to have protection in place against both viruses and spyware. I say this because I don't want to give you the impression that anti-virus software is unimportant: it's absolutely critical.