Myth #1: Ad networks are just a source of cheap, remnant inventory.
Reality: The ad networks of five years ago are practically unrecognizable today. For over a decade, the ad networks were essentially a repository for remnant inventory -- an efficient vehicle to unload inventory that couldn't be sold otherwise. However, the continued consolidation of the ad network business has drastically changed its definition.

The smaller, full-service networks, as well as some of the specialized ones like behavioral network Tacoda, have been absorbed into the major media companies. In the last few years, AOL has gone on a buying spree to build Platform A (consisting of Advertising.com, Tacoda and Quigo), Yahoo acquired Blue Lithium to form the basis of the Yahoo Ad Network and Google has steadily built its AdSense network.

As a result of this consolidation, the ad networks are no longer just a source of "bottom feeder" inventory, but are increasingly used as an alternative sales vehicle for inventory from premium content sites. It would be a stretch to say this inventory is no longer remnant, but the networks today certainly contain a substantial amount of premium inventory from high quality sites.

Media companies such as Yahoo and AOL, which may have previously distributed their remnant inventory to multiple networks, are increasingly allocating their remnant to their own networks. In essence, the network simply becomes another product offering from a suite of advertising solutions offered by the top publishers.

A singular definition for ad networks no longer works.