Page fraud is done by publishers loading many different ads onto one web page. Some of the many ads are visible, most are hidden. Sometimes they are hidden in layers, so that many ads are buried on top of each other and only the top one is visible. Sometimes the ads are hidden within iframes that are set to a super small 1-by-1 pixel size (= they’re not visible at all). In other cases they are rendered off the web page in hidden frames or layers.
It’s possible that a publisher using an ad unit provided by an ad network could be unaware that the network is doing something unscrupulous – at least at first. But they are like pizza shops that sell more pizzas than it’s possible to make with the flour they’ve purchased. They may be unaware of the exact nature of the bad behavior but must eventually realize that something funny is going on. In the same way, bad behavior is very clear to publishers who can compare the number of page views they’re getting with the number of ad impressions they’re selling.
Page fraud does not mean “viewability”. Viewability means: ads have been place either above-the-fold (= is an old newspaper term) or below-the-fold. Below-the-fold simply means: the user needs to scroll down the web page to see the ad. Ads placed below the fold by nature get less clicks than ads placed above-the-fold.
Helpful link: How to Generate Fake Ad Impressions (Presentation)
Helpful link: How to Generate Fake Ad Impressions (Presentation)
