This is the first post in a series about online advertising measurement and methodologies. Feel free to email me or post in the comments section about topics you’d like to see covered in this series. Curious about Chartbeat advertising tools? Learn more here.

What is viewability, you ask?

First things first: A viewable impression is a metric of online advertising that indicates if a display ad is actually viewable when it’s served. More specifically, the IAB and MRC define a viewable impression as one that’s at least 50% visible for at least one second.

Simply put, viewability is a metric that tracks if at least half of a display ad has the chance to be seen in the viewable portion of a browser window for at least one continuous second.

Note: technically speaking, the guidelines measure time in terms of 100 millisecond intervals, so a continuous second equates to 10 consecutive 100 millisecond observations. To add even more confusion, if the ad is 242,500 pixels or greater, only 30% needs to be in view. You can check out the full set of guidelines on the Media Rating Council’s website.

Back in March, the Media Ratings Council (MRC) lifted the advisory against using viewable impressions as a currency for buying, selling, and measuring advertising in the digital display space, marking the first time the industry has established a single measurement for viewability. (While viewability has been a topic for several years now, the MRC issued an advisory against transacting on viewable impressions in November 2012 due to known technological limitations. Removal of the advisory earlier this year gave marketplace players the go ahead to transact.)

Why is viewability such a hot topic of conversation?

Digital advertisers have been pushing for measurements that would give them a better sense of how many people their campaigns actually reach. Turns out, comScore found that up to 54% of display ads aren’t viewable as a result of things like rapid scrolling, ad placements that weren’t seen, and non-human (bot) traffic. Brand marketers were not too thrilled to find out they had been paying for ad impressions that nobody was seeing and called for a system with more accountability and transparency.

So, after much deliberation, enter IAB’s and MRC’s new standard of measurement. The hope among the trade body is that the new viewability standard will shift the entire currency of the industry from an impressions-served standard to an impressions-viewed one.

Big picture, what will this shift mean for the digital ad ecosystem?

In short, the way online media is sold is changing. On the demand side, advertisers are gaining more transparency and will expect guarantees on viewable display impressions in the future. Theoretically, this will improve campaign performance, as eventually, advertisers will only pay for ads that have the potential to be seen.

On the supply side, opinions are varied. Some publishers are concerned that this shift will have a negative impact on ad revenues since their supply of impressions to sell may be significantly reduced. This fear has already resulted in some publishers rethinking site design to increase viewability.

On the other hand, publishers that are focusing on premium ad experiences see this as a largely positive change. If a publisher can guarantee that ads are actually being seen by an engaged audience, it can leverage those high viewability percentages to demand higher costs for certain impressions. David Payne, Chief Digital Officer at Gannett, summed it up well in a recent post: “Viewability provides us another proof point that shows how our premium content creates highly engaged audiences perfect for branding campaigns.”

So, are people really adopting viewability as the standard?

Now that the viewability standard has been set (though some folks are questioning it), viewability requests are beginning to come in to direct sales teams. Major general interest publishers are already seeing more viewability requests, and expect to see an increase in requests in Q1 2015. Smaller, endemic publishers are initiating programs to research their own sites’ viewability, so as to prepare for when they too begin to encounter viewability requests in RFPs.

Up next in our series: “What Does Viewability Mean for Publishers?” Stay tuned…