More About Spyware
Strictly defined, spyware consists of computer software that gathers and reports information about a computer user without the user's knowledge or consent. More broadly, the term spyware can refer to a wide range of related malware products which fall outside the strict definition of spyware. These products perform many different functions, including the delivery of un-requested advertising (pop-up ads in particular), harvesting private information, re-routing page requests to illegally claim commercial site referral fees, and installing stealth phone dialers.
Spyware as a category overlaps with adware. The more unethical forms of adware tend to coalesce with spyware. Malware uses spyware for explicitly illegal purposes. Exceptionally, many web browser toolbars may count as spyware. On the other hand, adware may simply load ads from a server and display them while a user runs a program, with the user's permission; the software developer gets ad revenue, and the user gets to use the program free of charge. In these cases, adware may function ethically. If the software collects personal information without the user's permission (a list of websites visited, for example, or a log of keystrokes), it may become spyware.
Data collecting programs installed with the user's knowledge do not, technically speaking, constitute spyware, provided the user fully understands what data they collect and with whom they share it. However, a growing number of legitimate software titles install secondary programs to collect data or distribute advertisement content without properly informing the user about the real nature of those programs. These barnacles can drastically impair system performance, and frequently abuse network resources. In addition to slowing down throughput, they often have design features making them difficult or impossible to remove from the system.
In response to the emergence of spyware, a small industry has sprung up dealing in anti-spyware software. Running anti-spyware software has become a widely recognized element of computer security best practices for Microsoft Windows desktop computers. A number of jurisdictions have passed anti-spyware laws, which usually target any software that is surreptitiously installed to control a user's computer.