What is companion ads?
Companion ads are display units shown alongside a video or audio ad, such as a banner next to the player or an end card after the video, that extend the same campaign. In OpenRTB they are offered through Video.companionad and Audio.companionad, arrays of Banner objects, and Video.companiontype says which VAST companion resource formats the player can render.
Also called: companion ad, companion banner, end card, companionad.
How it works
Each companion slot is a full Banner object with its own size, position, and blocked attributes, and Banner.id should be unique within the impression. Video.companiontype lists accepted resource types from the AdCOM Companion Types list: 1 for a static resource such as an image, 2 for an HTML resource, and 3 for an iframe resource. Banner.vcm = 1 marks a companion that renders as an end card after the video, and 0 one that shows at the same time.
The companion creatives travel inside the VAST document, in its CompanionAds element, not as separate bids. VAST can mark companions as required (all, any, or none), which tells the player whether the main ad may play without them. Audio ads lean on companions more than video does, since a banner is the only visual part of the ad.
Pitfalls: offering companions on players that cannot show them, which is common in CTV apps; companion sizes in the VAST that match none of the offered banners; HTML companions returned when companiontype lists only static images; and counting companion slots as separate impressions in reporting.
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Related terms
Every term is in the glossary.