Spyware is a universal phrase used for software that executes certain behaviors such as advertising, collecting personal information, or changing the configuration of your computer, usually without properly acquiring your permission. Spyware is often associated with software that displays advertisements, known as adware. Adware is considered any software application in which advertising banners are displayed while the program is running. Adware runs, by "collecting information about the user in order to display advertisements in the Web browser, usually through pop-up windows, based on the information it collects from the user's browsing patterns." (What is adware?) Large media companies offer to place banner ads of their products, on websites, in exchange for a portion of the revenue from banner sales. This way, you don't have to pay for the software and the developers are still getting paid.
A person can get these spyware applications on their computer just by surfing the net or downloading music through a P2P program.
Examples would be Grokster, Kazaa, and Morpheus, for the P2P (Peer to Peer) programs. This seems to be the most common way of being infected by the spyware. Some examples of spyware itself, include, "Trojans, Web Bugs, Advertiser software (adware), and Stand-Alone Commercial Computer Monitoring/Surveillance software."(SpyCop)
One way to distinguish a virus from spyware is by its behavior. A virus seeks to infect a computer; to replicate; and ultimately, to infect as many computers as possible, as quickly as possible. Spyware tries to stay put, a behavior we typically associate with a parasite. "In the world of espionage, spyware is closest to a mole. A mole will avoid any activity that might blow his cover; similarly, spyware applications are often content to hide on your system." (Server Pipeline) Spyware disguises itself as a legitimate application so that it can collect...