Advertising-supported software (adware) includes any software application that automatically displays or downloads advertising banners while the program runs. This occurs after software installation or while the application is operating.

The advertisements are displayed through a bar or pop-up window that appears on the screen. The authors of the software include codes that prompt the delivery of the ads during software operation. Adware developers justify this by stating that these applications recover program development cost, thus keeping the cost low for the consumer.

Adware usually includes codes that tracks personal information and passes on that data to third parties, without the knowledge or authorization of the user. Some adware is also spyware, also called privacy-invasive software. Spyware has prompted protests from the Electronic Privacy Information Center (EPIC), and other privacy and security advocates.

Users may inadvertently download adware or spyware and may not know of it until advertisements pop up on their computers.

To avoid adware, users should not click on the pop-up ads. They should close the pop-up bar by using the task bar. This is done by right-clicking on the task bar entry, thus avoiding contact with the pop-up. E-mails with attachments should also be deleted, especially those from unknown people.

To keep your computer adware/spyware-free, you can use adware removal software. Adware/spyware uninstall software is easily available on the Internet. Users can usually get a free scan to diagnose infection.

Programs to detect and remove spyware have been developed. Many different examples of adware detection programs have also been created to detect and remove various adware applications. Programs such as Ad-Aware and Spybot-Search and Destroy are designed specially for spyware and not virus detection, though some antivirus software can detect both, or have a distinct spyware detection application.