Listen

Spyware, also called adware, is any software that secretly collects information about a computer and transmits the information to a a third party, usually for advertising purposes. It often leads to an annoying barrage of unwanted pop-up ads, and in sufficient quantity can damage your computer.

Dwight Silverman writes about computing for the Houston Chronicle.

SILVERMAN: Spyware can generate pop-ups that it pulls from a Web site or an advertising service. Sometimes these pop-ups can show up even when you are not browsing. The spyware runs in the background and brings you advertising pop-ups. I have seen some pieces of spyware that, when you click on something that generates a pop-up, instead of what you wanted you get a dozen other pop-ups that are advertisements. It can install unwanted search bars in the tool bar of your browser so it forces you to use their particular search engine, which in turn generates more advertising.

Where does spyware come from?

SILVERMAN: Usually it comes from Web sites that invite you to download something, or if you download a piece of software that appears to be useful and is usually free. The way they're able to afford the development of that software is usually to sell advertising within it, or to have some other process in it that talks to advertisers. You can also get spyware by going to a Web site that pops up what's called a "browser helper object certificate." It looks almost like a little stock certificate. It says, “Do you want to install this product that will improve your search function and get you free porn?” And yes, some of them say that. Hopefully most people will click no. But some people will click yes. And that installs the spyware.

What do the purveyors of spyware want from me?

SILVERMAN: They want to know what you are doing on the Web. They want you to look at their advertising. And they want you to buy their products. Why do they want to know what I'm doing on the Web?

Why do they want to know what I'm doing on the Web?

SILVERMAN: There is spyware that will target ads at you depending on where you go. So let's say, for example, that you're fond of going to gaming sites. They might pop up some ads for games.

How can spyware actually hurt your computer?

SILVERMAN: If you have enough of these programs that are talking to other Web sites, popping things up and hogging your bandwidth, they can really slow down both your Internet connection and the general performance of your PC. In fact, that's how most people realize they have spyware. They think the pop-ups are just coming from surfing the Web. They don't realize that their machine is slowing down because it is clogged with spyware.

Free Software for Removing Spyware:
Spybot Search & Destroy
Ad-aware
Hijack This

Bonus! Listen to more spyware tips from Dwight Silverman.