Adware

Adware (a combination of the words advertisement and software) is software designed to display advertisements. It is typically classified as a form of malware, though some sources rate less-intrusive adware as an irritant rather than malware, and most security vendors classify it as a potentially unwanted program (PUP) or potentially unwanted application (PUA).

How it works

Adware typically displays its advertising payloads on the desktop or through pop-ups instead of through a web page or other media. It is frequently bundled with free programs through installers rather than chosen by the user, and does not self-replicate the way a virus does.

Why it is a problem

Adware displays advertisements the user did not ask for and cannot easily control. Because it usually arrives bundled with other software rather than installed deliberately, users may not know it is present or how to remove it, and some adware changes browser or search settings to steer traffic toward advertisements. Some legitimate programs also display advertisements, which can blur the line between ad-supported software and unwanted software.

Examples

• McAfee has displayed advertisements through its own software products.