Third-party ad serving (3PAS)

1. Third-party ad serving (3PAS) is a model of ad delivery involving three parties: the publisher, the user, and the ad server. Rather than serve an ad directly to the user’s browser, the publisher delivers an ad tag, which redirects the browser to an ad server where the ad is stored.
2. May also refer to the server itself, as in: Campaign Manager 360 is a 3PAS.