Spyware is software or hardware installed on a computer without the user's knowledge which gathers information about that user for later retrieval by whomever controls the spyware.

Spyware can be broken down into two different categories, surveillance spyware and advertising spyware.

Surveillance software includes key loggers, screen capture devices, and trojans. These would be used by corporations, private detectives, law enforcement, intelligence agencies, suspicious spouses, etc.

Advertising spyware is software that is installed alongside other software or via activex controls on the internet, often without the user's knowledge, or without full disclosure that it will be used for gathering personal information and/or showing the user ads. Advertising spyware logs information about the user, possibly including passwords, email addresses, web browsing history, online buying habits, the computer's hardware and software configuration, the name, age, sex, etc of the user.

As with spam, advertising spyware uses the CPU, RAM, and resources of the user's computer, making the user pay for the costs associated with operating it. It then makes use of the user's bandwidth to connect to the internet and upload whatever personal information it has gathered, and to download advertisements which it will present to the user, either by way of pop up windows, or with the ad banners of ad-supported software. All of this can be considered theft in the cases of advertising spyware that installs without disclosure.

And while anti-virus software like Symantec's Norton Anti- Virus or McAfee's ViruScan can offer some protection, one of the best ways to combat spyware is with anti-spy software. Two of the best are Lavasoft's Ad-aware and Spybot's Search & Destroy, which are available as free downloads.

http://www.lavasoft.de/

http://www.safer-networking.org/en/index.html

The free version of Ad-aware does not proactively protect against spyware infestation. You have to start the Ad-aware application and initiate a scan to detect spyware. But the paid version, Ad-aware Plus does remain alert in the background, like Spybot, to deflect any attempts at infestation. In recent tests, Ad-aware Plus and Spybot both protected systems extremely well.

If you haven't already done so, I highly recommend installing Microsoft's Service Pack 2. SP2 tightens your PC's security with a new Windows Firewall, an improved Automatic Updates feature, and a pop-up ad blocker for Internet Explorer. Plus, the newly minted Security Center gives you one easy-to-use interface for keeping tabs on your PC's security apps.

There are also other steps you can take to protect against spyware. One simple step is to switch from Microsoft's browsers, which have security holes for spyware programs to exploit. A good alternative is Mozilla Firefox. Another not- so-simple step is switching to the Mac or Linux operating systems, which don't have spyware problems.