Banner is the easy case. Video, connected TV, and private deals each bend the rules: a different creative format, a sequence of ads instead of one slot, and guaranteed buys that never touch the open auction.

Video

Video uses VAST (the XML response format; VPAID is the older interactive variant) and the video mediaType. Instream runs before or during content (pre-roll); outstream is a video unit dropped inside an article. Video often runs s2s, because the bidders and creatives are heavier.

CTV

Connected TV uses ad pods (a sequence of ads in one break, like a TV commercial break) and SSAI (server-side ad insertion, stitching ads into the video stream on the server). CTV inventory is declared with app-ads.txt, the app and CTV cousin of ads.txt.

PMPs and deals

A PMP (private marketplace) sells to specific buyers via a deal ID, carried through Prebid as hb_deal. The flavors: preferred deal (first look at a fixed price), private auction (invite-only auction), and programmatic guaranteed (a fixed volume at a fixed price, a direct buy run programmatically).