Advertising Network (AD Network)

An advertising network (or AD Network) is a company that serves as an intermediary that connects advertisers that want to promote their offerings with publishers that have the available ad space or inventory to sell. An ad server is a piece of advertising technology used by ad networks, publishers, advertisers, and ad agencies to manage, run, and report on their advertising campaigns.

An ad network aggregates a large number of publishers to provide the required amount of inventory to the advertisers on an auction basis. In the early days of online advertising when there were fewer sites and advertisers, most publishers would only use one ad network to sell remnant inventory. However, as the number of publisher sites increased, they soon found that they weren’t able to sell all of their inventory on one ad network and suffered from low fill rates.

In an attempt to increase fill rates, publishers started using multiple ad networks, some of them offering premium inventory and others offering remnant inventory.