Advertisers have been demanding a change in the way ad inventory is purchased for many years. They are no longer willing to pay for ads that aren't considered viewable. But more intrusive ads aren't welcome either and many users are adopting ad blocking measures to fight back, including built-in ad blockers in the browser.

Beginning in January 2018, a 70 percent viewability standard for display ad campaigns will be broadly enforced. For a display ad to be viewable, at least 50 percent of the ad must be within the viewport for at least one second (two seconds for video). Sites with programmatic advertising inventory less than 70 percent viewable will see a dramatic drop in fill rate and eCPMs.