InformationWeek SMB TechEncyclopedia

(1) (ADvertisementWARE) Software that periodically pops up advertisements on a user's computer. It displays ads targeted to the individual user based on key words entered in search engines and the types of Web sites the user visits. The marketing data are collected periodically and sent in the background to the adware Web server. Adware is known as "contextual marketing."

Adware or Spyware?
If adware is installed in the user's machine without disclosure, it is considered "spyware." Such programs are often delivered as part of another download the user actually did want, but without any notification. Since software licenses are rarely read, there is controversy over what is legitimate adware versus spyware. See contextual marketing, popup ad, PUP and spyware.

(2) (AD supported softWARE) Software that is given away for free because advertising messages appear on a regular basis. See adserver.