In general terms Adware also known as advertising-supported software can be described as any software which automatically displays, plays, or downloads advertisements to a computer after it has been installed or when the application is being used. You must also remember that some types of adware could also be spyware which can monitor your computer and internet usage.

The main function of this software is to present advertising pertinent to the types of goods or services featured in that particular site which the user is browsing. Adware is usually a way to recover development costs, and in some cases it may allow the software to be provided to the user free of charge or at a reduced price. Conversely, the advertisements may be seen by the user as interruptions or annoyances or as distractions from the task at hand.

If your computer has been infected with viruses like adware or spyware you can get help from special programs like Ad-Aware or Spybot-Search & Destroy which are specifically designed to detect, quarantine and remove viruses. Moreover, you could also download some commercial antivirus software which enables you to detect adware and spyware.