Adware

The 2003 Microsoft Encyclopedia of Security and some other sources use the term "adware" differently: "any software that installs itself on your system without your knowledge and displays advertisements when the user browses the Internet",[2] i.e., a form of malware.

Some developers offer software free of charge and rely on advertising revenue to recoup their expenses and generate income.

[8] Examples of advertising-supported software include Adblock Plus ("Acceptable Ads"),[9] the Windows version of the Internet telephony application Skype,[10] and the Amazon Kindle 3 family of e-book readers, which has versions called "Kindle with Special Offers" that display advertisements on the home page and in sleep mode in exchange for substantially lower pricing.

[4] In the view of Federal Trade Commission staff,[21] there appears to be general agreement that software should be considered "spyware" only if it is downloaded or installed on a computer without the user's knowledge and consent.

Much of the discussion on the topic involves the idea of informed consent, the assumption being that this standard eliminates any ethical issues with any given software's behavior.

[22] The term adware is frequently used to describe a form of malware (malicious software)[23][24] which presents unwanted advertisements to the user of a computer.

[35] Programs have been developed to detect, quarantine and remove advertisement-displaying malware, including Ad-Aware, Malwarebytes' Anti-Malware, Spyware Doctor and Spybot – Search & Destroy.

[35] Adware has also been discovered in certain low-cost Android devices, particularly those made by small Chinese firms running on Allwinner systems-on-chip.

There are even cases where adware code is embedded deep into files stored on the system and boot partitions, to which removal involves extensive (and complex) modifications to the firmware.

[37] In recent years, machine-learning based systems have been implemented to detect malicious adware on Android devices by examining features in the flow of network traffic.