How to Setup Backfill to Sell Your Remnant Ad Impressions

Reading time: 6 minutes

Having extra unsold ad space as a digital ad publisher[16] is inevitable and unpredictable. While this space is no longer considered premium ad inventory[17][7], advertisers know every ad impression[8] counts and remnant[18] inventory definitely has its value. In fact, as a low-cost option, remnant ad inventory can be quite attractive for small and medium-sized businesses trying to connect with their audience online in every way possible. 

How can you set up channels to unload your remnant ad impressions in order[19] to maximize your company’s efficiency and productivity? Here’s a look at tips for setting up backfill[20] using tools commonly available in Google Ad Manager[1] and other routes. 

How can a publisher backfill an unsold ad inventory?

As a publisher, you can fill unsold ad impressions by using an ad server such as Adsense, Google Ad Exchange[9], or Header Bidding[10]

AdSense is a program run by Google that matches ads to website content and users visiting a site online. This is one of the best digital ad networks out there when it comes to servicing small and medium-sized publishers. 

Case I: Google Ad Manager > Waterfall > AdSense

If you are publishing ad impressions through Google but Adsense isn’t filling all your inventory with ads, consider waterfalling. At its core, the Google waterfall method is a process model used in software development. This technique splits a project into several sections, and rules stipulate that a new section can’t be started until the one before it has been finished. 

With online advertising, this means a ladder of networks are ordered top to bottom according to their past performance[11] when trying to sell an ad impression. This ladder of networks is presented to the publisher. The ad impression is then moved from the top of the ladder to the bottom until it’s sold in a real-time auction. 

The impression is redirected from one network to the next in a daisy-chaining process. The further up the ladder it’s sold, in theory, the more money you make as a publisher. Ideally, the CPM[2] price drops as you move down the ladder, ensuring nothing is left unsold and the best possible price is obtained. 

Waterfalling is not so clear cut  in practice, however. One drawback to this method is that it can lead to higher latency, (ads taking more time to load). It can also result in an ad impression being sold at a lower price before reaching a network that’s home to someone willing to pay a higher price. So, waterfalling can be a good solution but it doesn’t always produce an optimal yield[21]. It’s worth a shot, however. 

Outside of Adsense, as a publisher, you can set your own ads up in a waterfall. In order to optimize performance, you can also arrange a guaranteed deal with a certain third party[12] ad network[13]. This should be one that promises you access to better CPM rates. This will allow this particular network to serve ads before others.  

As a final choice, if there isn’t an ad network that can deliver the ad impressions, you can serve them yourself with a “house line item[22]”. These are typically ads that promote your own products and services. 

Case II: Google Ad Manager > AdX/AdSense

Google AdX, (also known as Google Ad Exchange), is a digital ad exchange focused on supplying private auctions, real-time biddings (RTB[3]), and preferred deals. GoogleAdX gives you, as a publisher, more control over your ad space, and allows you to sell your ad inventory directly. This is the world’s biggest exchange of global ad inventory and it can set you ahead by allowing you to sell impressions of ads rather than clicks.

Most users of Google AdX are large publishers. Your membership needs to be manually approved by a Google employee in order to access the exchange, and there are certain qualifications you need to meet. For example, you will need to be a preferred publisher with a minimum of 5 million monthly pageviews

AdX is advantageous as it provides you with access to premium ad campaigns that you don’t encounter in AdSense. 

To use Google AdX to backfill your remnant ad impressions, sign up for a Google AdX account. You can find instructions on how to do that here.

Next, decide to use if you want to:

  1. Have Google run AdX and AdSense simultaneously to fill your ads
  2.  Disable AdSense and use AdX only
  3. Use AdSense only

To set AdSense as your backfill:

  • Go to the Google Ad Manager homepage
  • Click on Inventory > Ad units
  • Select the ad unit[23] you wish to backfill ad impressions
  • Enable Maximize revenue of unsold inventory with AdSense

To have AdSense backfill across your entire network:

  • Go to Inventory > Network settings
  • Select “Maximize revenue of unsold inventory with AdSense”

Using waterfall techniques and optimizing AdSense and AdX to backfill your remnant ad impressions can work. It’s important to know these tactics can still leave you with unsold ad inventory, however. In order to tackle the issue, consider header bidding as described below.  

Case III: Header Bidding > Google Ad Manager > Ad Exchange

Header bidding is a process that allows publishers to offer ad inventory to many ad exchanges at the same time. The advantage is you can do this before you make calls to your ad servers[14], requesting them to conduct ad campaigns online. This is sometimes called “advance bidding” or “pre-bidding”. 

Basically, unlike with waterfalling, header bidding allows the highest bid to win the ad inventory. 

To enable header bidding you can:

  • Use Prebid
  • Take advantage of Freestar’s header bidding solutions (ours)
  • Enable a line item to serve ads from your Prebid winner. Define this order as a “price priority” so that line items with the highest CPM ultimately serve an ad to the user. Google Ad Manager compares this winning CPM price with guaranteed deals. Google serves ads from the highest bidder[24], which can be Prebid, a GAM[4] guaranteed line item[5], or AdX. 

What’s after header bidding?

Sometimes, even with header bidding, none of your demand partners returns a bid within the time you specified as a publisher. They also may have had no valid ads to supply. While this situation is uncommon, it can happen. In this case, Prebid will pass the empty item back to the ad server. The server will look for eligible line items. If nothing results, you can run AdSense as your backfill. It’s advisable to move your best demand partners to the client-side as this can result in a better fill rate[25]

What can you do when backfill networks are also not filling the inventories?

Google Ad Manager also allows you to serve backup ads for your unsold inventory. These can only be in the form of a static image or an HTML page. When you select “static image”, as a publisher, you can show GIF format ads sourced from any other URL. 

With HTML back up ads, you can present an HTML page users can click on and be directed to another link. This can increase engagement and impressions on both pages. (As a side note, it’s good to know this feature is only for publishers who use Google Exchange demand). 

To create a backup ad in Google Ad Manager:

  1. On the Google Ad Manager home page, click Inventory > Ad Exchange rules > Ad types &amp[6]; backup ads
  2. Select your inventory type (Display) 
  3. Create a new style or use an existing one
  4. Set your targeting[26] criteria for your ad inventory
  5. Select ad types 
  6. Choose to show blank space or other ads from another URL
  7. Save your settings 

What’s next?

You can backfill your remnant ad space with any advertiser[15] or demand partner. To get creative[27], consider running affiliate marketing banners on your unsold inventories. 

Of course, it can take time to see results. If you aren’t gaining the results you want with your ad inventory, contact us here and we can help optimize your setup. 

1. Google Ad Exchange ( Google Ad Manager ) Ad Exchange is often referred to as the premium version of AdSense, and also a Google-owned ad network of sorts. To join Ad Exchange, publishers need to meet specific requirements such as 500 000 minimum monthly traffic, be invited or join through a Google certified partner. Recently Google has rebranded this product, and it is now called Google Ad Manager.
2. Cost Per Mille/Thousand [CPM] ( CPM ) Cost per mille, or thousand (mille = thousand in Latin). A pricing model in which advertisers pay for every 1000 impressions of their advertisement served. This is the standard basic pricing model for online advertising. See also CPC and CPA.
3. Real-Time Bidding [RTB] ( RTB ) Real-time bidding is a technology-driven auction process where ad impressions are bought and sold almost instantaneously. Once an advertiser wins a bid for an ad impression, their ad is shown on a website. Real-time bidding plays a crucial part in the digital advertising ecosystem together with other players such as ad exchanges and supply side platforms.
4. Google Ad Manager ( GAM ) Google Ad Manager is a combination of both Google Ad Exchange and DoubleClick For Publishers as a unified platform that provides publishers with ad serving services.
5. guaranteed line item. These are line items that a publisher contractually require to be served a specific number of impressions with additional specifics such as ad size, traffic geography, etc. The ad manager would ensure deliverance by reserving ad inventory for this line item.

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