How to Scan for and Remove Spyware

Before you take drastic measures to remove spyware from your computer, read our tips.
Before you take drastic measures to remove spyware from your computer, read our tips.
© ­iStockphoto/Smithore

­While you're reading this, it's possible someone is watching you. It could be a malicious hacker logging your every keystroke to gain access to your personal information. It could be an advertising company tracking your activity in order to serve up targeted advertisements. Or maybe it's a company determined to guide you to specific Web sites whether you want to visit them or not.

The tool these people and organizations use to affect your browsing experience is called spyware. Spyware is any sort of application that hides in the background and either manipulates or tracks your Web browsing experience. Spyware that tracks you in order to serve up advertising is also called adware.

These applications fall into a spectrum that stretches from merely irritating to completely disruptive. In a best-case scenario, spyware will make your Web browsing experience an annoying one as you try to navigate through pop-up ads, avoid bogus search results or deal with a slow and unresponsive Web browser. At worst, spyware will log your activities and send that information to someone else who might use it to steal your identity.

­Your computer can become infected with spyware very easily. Pop-up ads can hide spyware -- clicking on one could prompt your browser to download an unwanted application. That's why it's a good idea to click only the X button on a pop-up ad rather than the Cancel button. Spyware can also piggyback onto a legitimate application. You may have seen examples of this in the form of various toolbars. It's important to pay attention to downloads and installations if you want to avoid spyware.

But what if you have spyware on your computer already? What's the best course of action? It all starts with a spyware scanner.

Scanning and Removing Spyware

Let's say you know something is wrong with your Web browser. Maybe you're redirected to a strange search engine when you really just want to go to Google. Or perhaps you keep getting buried in pop-up ads no matter what site you visit. What do you do?

The first step is to download and install anti-spyware software. There are several applications that will scan your computer for spyware. Some of them are free. Here's a short list of popular anti-spyware applications:

  • Ad-Aware (
  • Microsoft Windows Defender (
  • PC Tools Spyware Doctor (
  • Spy Sweeper (
  • STOPzilla (
  • Sunbelt Software CounterSpy (

Resist the temptation to download and install more than one application -- anti-spyware software can eat up your computer's processing power while it scans your system. Running multiple anti-spyware applications may slow your computer to a crawl. And sometimes anti-spyware applications will conflict with each other and cause your computer to crash. Check to see if the anti-virus software you use has an anti-spyware capability. If it does, you should just run the anti-virus application.

The anti-spyware software will scan your computer and look for evidence of spyware applications. Most anti-spyware applications will quarantine anything they identify as spyware automatically. Next, most of the applications will allow you to review the spyware applications found on your machine before you delete them. It's usually a good idea to delete spyware once you detect it.

The only other thing to keep in mind is that you should always make sure your software is current. If there is an option to receive automatic updates to your anti-spyware software, you should activate it. Otherwise, be sure to check with the vendor on a regular basis -- new spyware hits the Internet every day.

Once your computer is clean, you can keep it free from spyware through some careful Web surfing. Watch out for piggybacking when you install applications. Don't click on pop-up ads. And don't click on any windows that claim your computer needs a spyware scan -- doing so may actually download spyware to your machine.

Learn more about spyware and other software that goes bump in the night on the next page.

Related HowStuffWorks Articles


  • Microsoft. "Protect your computer: Beyond the Basics." (Apr. 1, 2009)
  • Spyware Guide. (April 1, 2009)
  • Symantec. "Crimeware: Trojans & Spyware." (April 2, 2009)
  • Federal Trade Commission. "Spyware." July 2005. (April 2, 2009)