Viewability is one of the most important KPI for websites. It allows buyers to know how many ads are really viewed to the users. When a webpage is loaded all the ads send a request to Google and probably all of them return an Impression, whether they are above the fold or below the fold. Specially for the very long webpages, likely the users will not scroll all the article and they will not see the last ads. Viewability try to explain exactly this; it tells how many time a single ad is viewed! The Interactive Advertising Bureau (IAB) defines a viewable banner impression when 50% of the ad's pixels are shown for at least 1 second, while in-stream video it needs at least 2 seconds.
15 Tips and Best practices
ExMarketPlace uses Lazy Loading tecnology (or Smart Loading) to improve Viewability. It allows us to load ads only when necessary, or in other words, when users scroll down till the monetized area. In this way the percentage of Ad Impressions will be very similar to the ads viewed and the site will be faster because of a lower number of Low quality Impressions. ExMarketPlace is able to create a perfect customized setup for each site, evaluating how many pixels are needed before appearing on the user's screen to start loading them.