Software that sends information about your Web surfing habits to its Web site. Often quickly installed in your computer in combination with a free download you selected from the Web, spyware transmits information in the background as you move around the Web. Also known as "parasite software," "scumware," "junkware" and "thiefware," spyware is occasionally installed just by visiting a Web site (see drive-by download).|
Spyware May Even Identify Itself
The license agreement that nobody ever reads may actually state that you are installing spyware and explain what it does. For example, it might say that the program performs anonymous profiling, which means that your habits are being recorded, not you individually. Such software is used to create marketing profiles; for example, people who go to Web site "A" often go to site "B" and so on. Spyware may deliver competing products in real time. For example, if you go to a Web page and look for a minivan, an ad for a competitor's vehicle might pop up (see adware).
Spyware Is Focused
Merchants place ads with spyware advertisers because they feel their promotions are focused. In fact, many feel that the Internet has opened up the most intelligent marketing system the world has ever seen. Merchants say they are targeting prospects who are really interested in their products, and spyware vendors argue that as long as they treat users anonymously, they are not violating privacy.
There are also spyware programs that keep changing the home page in the browser to a particular Web site or just keep popping up ads all the time (see adware). Nevertheless, once you detect spyware, it can be eliminated, albeit with difficulty sometimes.
Spyware blockers can detect an invasion of spyware into your computer and have become as popular as antivirus programs. See PUP, spyware blocker, adware, snoopware, parasite and spam.
Spyware Vs. Viruses
Since spyware and adware are unwanted software, it would seem that antivirus software should detect spyware and adware as well as viruses and Trojans. Although some security suites provide all these capabilities, antispyware and antivirus modules are typically separate functions.
Perhaps, it evolved in different camps because the intent of the software is different. Virus writers want to be exposed to the world at large so they can one-up their peers, the "xyz virus contaminated 100 million computers" type of glory. On the other hand, spyware writers want their software to remain hidden and perform their tasks for months to come.
However, Trojans are viruses that are designed to remain hidden in the computer as well, so the two philosophies do overlap. Perhaps, in time, a new category of "anti-insanity" software will take care of all of it.