Simply put, Whitelisting is the process of adding a certain publisher and his offered ad space to a list of preferred publishers you want your ads to at. With a whitelist in place, your ads will run at the selected publisher’s ad space and nowhere else. So basically a whitelist is the exact opposite of a blacklist.
A whitelist can be a powerful tool for marketers to provide better control of where their ads are running. As the delivery of ads in online and mobile marketing becomes increasingly intransparent through prorammtic advertising, a whitelist can be very beneficial for advertisers. Instead of running your ad everywhere right from the beginning you start out by building a list of preferred placements and build up scale over time.
If advertisers have a whitelist in place and use it correctly, they can be sure that the people seeing their ads are also the people who are most likely to be their next clients or customers. Accordingly, this reduces the risk of ads reaching an irrelevant audience. Apparently, whitelisting is a good approach for advertisers to get the most out of their ad spend.