Pragas Internet

[BladeRunner]

"Adware, or advertising-supported software, is any software package which automatically plays, displays, or downloads advertisements to a computer. These advertisements can be in the form of a pop-up. The object of the Adware is to generate revenue for its author. Adware, by itself, is harmless; however, some adware may come with integrated spyware such as keyloggers and other privacy-invasive software."

Adware: http://en.wikipedia.org/wiki/Adware

"Most adware is spyware in a different sense than "advertising-supported software," for a different reason: it displays advertisements related to what it finds from spying on the users."
Ora, isto só acontece quando integrado em adware!
Spyware, por si só é isto:

"Spyware is a type of malware that can be installed on computers and collects little bits of information at a time about users without their knowledge. The presence of spyware is typically hidden from the user, and can be difficult to detect. Typically, spyware is secretly installed on the user's personal computer. Sometimes, however, spywares such as keyloggers are installed by the owner of a shared, corporate, or public computer on purpose in order to secretly monitor other users.

While the term spyware suggests that software that secretly monitors the user's computing, the functions of spyware extend well beyond simple monitoring. Spyware programs can collect various types of personal information, such as Internet surfing habits and sites that have been visited, but can also interfere with user control of the computer in other ways, such as installing additional software and redirecting Web browser activity. Spyware is known to change computer settings, resulting in slow connection speeds, different home pages, and/or loss of Internet or functionality of other programs. In an attempt to increase the understanding of spyware, a more formal classification of its included software types is captured under the term privacy-invasive software."

Spyware: http://en.wikipedia.org/wiki/Spyware

Parece que eu acertei no que disse anteriormente!
O adware, na sua maioria, comporta spyware... o inverso não acontece!