Advertising network

Online advertising network or ad network is a company that connects advertisers to web sites that want to host advertisements. The key function of an ad network is aggregation of ad space supply from publishers and matching it with advertiser demand. The phrase "ad network" by itself is media-neutral in the sense that there can be a "Television Ad Network" or a "Print Ad Network", but is increasingly used to mean "online ad network" as the effect of aggregation of publisher ad space and sale to advertisers is most commonly seen in the online space. The fundamental difference between traditional media ad networks and online ad networks is that online ad networks use a central Ad server to deliver advertisements to consumers, which enables targeting, tracking and reporting of impressions in ways not possible with analog media alternatives.


The advertising network market is a large and growing market, with the top 20 companies earning about $2 billion in revenues during 2007. This represents around 13% of the total display advertising market, forecasted to grow to 18% by 2010. This growth has resulted in many new players in the market, and has encouraged acquisitions of ad networks by large companies entering the market.
Ad networks are primarily involved in selling space for online ads to appear. This online advertising inventory comes in many different forms, including space on websites, in RSS feeds, on blogs, in instant messaging applications, in adware, in e-mails, and on other sources. The dominant form of inventory continues to be third-party websites, who work with advertising networks for either a fee or a share of the ad revenues.