Plainly put, ad viewability and verification measures what percentage of an ad is viewable on the screen and for how long. Desktop viewability measurement is much more mature and standardized then what exists for mobile, and is further delineated by screen size and how users interact with it. Due to the size of mobile screen sizes and how users navigate mobile properties, advertisers have become very concerned about how long if at all ads are visible on mobile devices.
The majority of mobile devices have small screen footprints so ads situated at the top or bottom of the layout may be only visible for a short period of time if at all. In addition, mobile users tend to scroll up and down quickly, so if an ad is slow to load a user may bypass it before it ever displays.
On desktop the screen size is larger so more content is in view, users tend to not scroll as quickly and page elements tend to load quicker since connections are usually through a landline rather than wireless. Even with these characteristics, recent studies have surprisingly shown that viewability on mobile may be higher than desktop.
Unfortunately there are no standards in place for mobile viewability and the lack of this type of measurement has been cited by some as a major factor limiting the growth of the mobile ad industry. A recent viewability study from Moat found that as much as 56% of mobile ads are not completely visible. In response, some ad platforms have begun offering to only bill when ads are viewable for a certain amount of time. Facebook recently rolled out a new video ad program option where they only bill for ads in which the viewer has watched at least 10 seconds.
Further complicating the matter are the challenges between measuring viewability on mobile websites compared to apps. Most companies have a solution for mobile web measurement, but it is much more difficult to measure in app. The solutions that do exist require the integration of the companies SDK within the app. Many app developers are hesitant to add any additional SDKs to their app which is limiting the adoption of in app viewability measurement.
The MRC (Media Rating Council) is working hard to release a standard for mobile ad viewability by the end 2015, but until then many mobile ad verification companies are working to provide their own solution and position themselves as leaders within the space. Once the standards are released it will be interesting to see how the verification industry shakes out, but it is clear that mobile ad viewability measurement is something that is here to stay.