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What Is Spyware?
Some people mistake spyware for a computer virus. A computer virus is a piece of code designed to replicate itself as many times as possible, spreading from one host computer to any other computers connected to it. It usually has a payload that may damage your personal files or even your operating system.
Spyware, on the other hand, is generally not designed to damage your computer. Spyware is broadly defined as any program that gets into your computer without permission and hides in the background while it makes unwanted changes to your user experience. The damage it does is more a by-product of its main mission, which is to serve you targeted advertisements or make your browser display certain websites or search results.
What Does Spyware Do?
Spyware can do any number of things once it is installed on your computer.
At a minimum, most spyware runs as an application in the background as soon as you start your computer up, consuming RAM and processor power. It can generate endless pop-up ads that make your Web browser extremely slow, to where it sometimes becomes unusable. It can reset your browser's home page to display an ad every time you open it. Some spyware redirects your Web searches, controlling the results you see and making your search engine practically useless. It can also modify the DLLs (dynamically linked libraries) your computer uses to connect to the Internet, causing connectivity failures that are hard to diagnose.
Certain types of spyware can modify your Internet settings so that if you connect through dial-up service, your modem dials out to expensive, pay telephone numbers. Like a bad guest, some spyware changes your firewall settings, inviting in more unwanted pieces of software. There are even some forms that are advanced enough to know when you try to remove them in the Windows registry and intercept your attempts to do so.
The point of all this from the spyware makers' perspective is not always clear. One reason it's used is to pad advertisers' Web traffic statistics. If they can force your computer to show you tons of pop-up ads and fake search results, they can claim credit for displaying that ad to you over and over again. And each time you click the ad by accident, they can count that as someone expressing interest in the advertised product.
Another use of spyware is to steal affiliate credits. Major shopping sites like Amazon.com and Ebay.com offer credit to a Web site that successfully directs traffic to their item pages. Certain spyware applications capture your requests to view sites like Amazon and Ebay and then take the credit for sending you there.
What Can I Do?
There are several applications you can turn to for trustworthy spyware detection and removal, including Ad-aware, Spybot and Windows Defender. All three are free for the personal edition. They work just like your anti-virus software and can provide Real-Time Protection and detection. They will also detect Internet cookies and tell you which sites they refer back to.
Use a pop-up blocker.
Many of the current browsers, including Internet Explorer 6.0 and Mozilla Firefox 1.0, have the ability to block any Web site from serving you pop-up windows. This function can be configured to be on all of the time or to alert you each time a site wants to pop up a new window. It can also tell you where the pop-up is originating from and selectively allow windows from trusted sources.
Most browsers have security settings in their preferences which allow you to specify which actions Web sites are allowed to take on your machine. Since many spyware applications take advantage of a special code in Windows called Active-X, it's not a bad idea to simply disable Active-X on your browser. Note that if you do this, you will also disallow the legitimate uses for Active-X, which may interfere with the functionality of some Web sites.
Be suspicious of installing new software.
In general, it pays to be suspicious when a site asks to install something new on your computer. If it's not a plug-in you recognize, like Flash, QuickTime or the latest Java engine, the safest plan of action is to reject the installation of new components unless you have some specific reason to trust them. Today's Web sites are sophisticated enough that the vast majority of functionality happens inside your browser, requiring only a bare minimum of standard plug-ins. Besides, it never hurts to reject the installation first and see if you can get on without it. A trustworthy site will always give you the opportunity to go back and download a needed component later.
Use the "X" to close pop-up windows.
Get to know what your computer's system messages look like so that you can spot a fake. It's usually pretty easy to tell the difference once you get to know the standard look of your system alerts. Stay away from the "No thanks" buttons if you can help it, and instead close the window with the default "X" at the corner of the toolbar. For an even more reliable option, use the keystroke combination for "close window" built into your software. You can look in your browser's "File" menu to find it.