GroupM and Unilever only count display impressions where 100% of an ad is in view for any length of time and video where 100% of the player is in view; at least half the ad plays; the sound is on; and a person actually clicks to start it. Conde Nast became the first major publisher […]

As far as Facebook is concerned, therefore, an ad is viewable the instant any part of it appears on a users’s screen. “As soon as an ad comes into view it starts creating value for the advertiser,” Mr. Smallwood said. Marketers Push Back on MRC Ad Viewability Standards – CMO Today – WSJ