Adware or
advertising-supported software is any software package which automatically plays, displays, or downloads advertising material to a computer after the software is installed on it or while the application is being used. Some types of adware are also spyware and can be classified as privacy-invasive software .
Adware is software with advertising functions integrated into or bundled with a program. It is usually seen by the programmer as a way to recover programming development costs, and in some cases it may allow the program to be provided to the user free of charge or at a reduced price. The advertising income may allow or motivate the programmer to continue to write, maintain and upgrade the software product.
Some adware is also shareware , and so the word may be used as term of distinction to differentiate between types of shareware software. What differentiates adware from other shareware is that it is primarily advertising-supported. Users may also be given the option to pay for a "registered" or "licensed" copy to do away with the advertisements.
The Eudora e-mail client is a popular example of an adware "mode" in a program. After a trial period during which all program features are available, the user is offered a choice: a free (but feature-limited), an ad-supported mode with all the features enabled, or a paid mode that enables all features and turns off the ads. If the user choose the ad-supported mode, Eudora becomes adware, although according to Qualcomm the program does not collect any information about user activity.