Viewability

Viewability refers to whether an online ad actually appears on a user’s screen in a way that they might see it. For an ad to be considered viewable, most standards say at least 50% of its area should be in the user’s view for at least a second (for display ads) or two seconds (for video ads). This helps advertisers ensure their ads reach real viewers rather than being counted just because they loaded somewhere on a webpage that the user never scrolls to or notices. Essentially, viewability measures the likelihood that an ad is actually seen by a person.