Browse Definitions:

What is spyware?

Learning Guide Table of Contents:

What is spyware?
Why spyware isn't just a home-user problem
How spyware gets in your computer
How you can prevent spyware
How you can clean up spyware

What is spyware?

In general, spyware is any technology that aids in gathering information about a person or organization without their knowledge. Internet advertising (adware) has been criticized for sometimes including code that tracks a user's personal information and passes it on to third parties without the user's authorization or knowledge. This practice has been dubbed spyware and has prompted an outcry from computer security and privacy advocates, including the Electronic Privacy Information Center.

Noted privacy software expert Steve Gibson of Gibson Research explains: "Spyware is any software that employs a user's Internet connection in the background (the so-called 'backchannel') without their knowledge or explicit permission. Silent background use of an Internet 'backchannel' connection must be preceded by a complete and truthful disclosure of proposed backchannel usage, followed by the receipt of explicit, informed consent for such use. Any software communicating across the Internet absent of these elements is guilty of information theft and is properly and rightfully termed: Spyware."

Spyware doesn't actually attempt to "take over" your computer, but it does try to do certain things you probably won't like. Here are some common signs that you have been infected:

  • Your PC is running unusually slow.

  • Ads are popping up even when your browser isn't running.

  • Your home page has been hijacked.

  • Antispyware and/or antivirus applications aren't working correctly. Some spyware programs will sabotage the programs designed to detect and eliminate them.

  • There's been a dramatic increase in your network's traffic, eating up bandwidth and crippling performance.

Read our complete definition. has a definition of spyware.

Top ten spyware threats
This list describes the ten spyware threats most frequently identified by Webroot's Spy Audit.

Spyware Guide
Spyware guide has an extensive list of software that has been identified as spyware.

More resources about spyware, adware and Trojans from TechTarget.

Spyware legislation sparks concern
This installment in a two-part series examines legislative effectiveness in handling spyware.

Fight spyware
A whole new category of software has exploded into life lately, with intentions that are far from honorable. These programs, called adbots, media plug-ins, backdoor Santas or Trojans, are known collectively as spyware.

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This was last updated in March 2011

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