Definicija: An ad that is served to a user's screen either as a pushed (sent by e-mail) or pulled ad (requested by a user's browser). This includes measurement of responses from an ad delivery system to a user's browser.

Definicija: The successful display of an advertisement on a user's computer screen.

Definicija: The ratio of clickthroughs to ad impressions.

Definicija: The series of ads displayed to a user during a single visit to a site.