Software that secretly sends data from a computer or mobile device to a central server for some type of processing. Spyware is commonly deployed for marketing, but it is also used for malevolent purposes (see Pegasus
Mostly for Web Behavior
Commonly used to gather Web surfing habits in the background without the user being aware, spyware is often installed in combination with a free download from the Web. Also known as "parasite software," "scumware," "junkware" and "thiefware," spyware is occasionally installed just by visiting a website (see drive-by download
Spyware May Even Identify Itself
The license agreement that nobody reads may actually state that data are being captured for advertisers. It might say that the program performs "anonymous profiling" in order to create marketing profiles; for example, people who go to website "A" often go to site "B" and so on. See adware
Spyware Is Focused
Merchants place ads with spyware advertisers because they believe the Internet is the most intelligent marketing system ever created and that their promotions are highly targeted. Merchants believe they are reaching prospects who are really interested in their products, and spyware vendors claim that as long as they treat users anonymously, they are not violating privacy.
Some Spyware Is Not So Hidden
There are spyware programs that keep changing the home page in the browser to a particular website or just keep popping up ads all the time (see adware
). Nevertheless, once spyware is detected, it can be eliminated, although sometimes with difficulty. Spyware blockers can detect an invasion of spyware and have become as popular as antivirus programs. See PUP
, spyware blocker
Spyware vs. Viruses
Software to combat spyware and viruses evolved in different camps because the intent is different. Spyware writers want their software to remain hidden and perform their tasks for months to come. In contrast, virus writers want to eventually be exposed to the world at large so they can one-up their peers for having contaminated more computers than anyone previously.