What is an Ad Network?

An Ad Network is a company that connects websites with advertising to sell, then aggregates that inventory for advertisers to buy, usually via programmatic exchanges. Another way to think about it is that ad networks are the sales representatives that sell the inventory hosted by websites within their network. Ad networks help by bringing together inventory, and more to the point, audiences, to enable marketers to buy online ad impressions faster, more efficiently and, yes, more cheaply.

The inventory of online advertising space comes in many different forms, including space on desktop and mobile websites, on blogs, mobile apps e-mails and on other media. An advertiser can buy a run of network package, or a run of category package within the network. The advertising network serves advertisements from its central ad server, which responds to a site once a page is called. A snippet of code is called from the ad server, that represents the advertising banner.