Spyware is a piece of software that spies on the machines it is installed on.

The goal is often to collect personal information, usually without the user's comprehension.  But there are many other things spyware can be used for.  So most spyware programs do not have harmful payloads in the usual sense of viruses, trojan horses or worms.  But their danger lies in the sorts of information they can collect, how it might be disseminated and how much computing resources they consume.

The following is a list of a variety of things spyware might be used for.

• marketing
  • showing ads while the user browses
  • collect website browsing history
• traffic redirection
  •  taking users to sites they didn't intend
• criminal purposes
  • stealing passwords
  • stealing credit card numbers
  • look for information stored in a computer's file system
  • logging keystrokes

Users are usually tricked into installing spyware by a variety of means.

Spyware can be installed for a number of false purposes.

• storing and organizing login and password information
• web browser toolbars

Spyware usually doesn't self-replicate.

Some of the most common spyware names are

• Gator
• BargainBuddy
• Bonzai Buddy
• 180 Solutions
• Internet Optimizer

Protection.  The single best approach to protecting your system from spyware is to never download an/or install that has uncertain sources, security and integrity.  A good up-to-date virus scanning program should help considerably with detecting known spyware that has gotten installed on a system.  Such scanning software should also help to detect and prevent installation of spyware.

Some examples of anti-spyware programs or security systems that include spyware capabilities are listed below.

• McAfee
• Norton's/Symantec
• Microsoft Defender
• Microsoft Vista claims to have effective anti-spyware capabilities installed with the operating system
• Ad-Aware
• Spyware Detector

It shouldn't be too surprising that some of these spyware scanners report the presence of their competitor's software as spyware.  There has been some publicity about such curious and conflicting claims.

More will be added.