Google Adwords - Adnetwork

An advertising network or ad network is a company that connects web sites that want to host advertisements with advertisers who want to run advertisements. Companies that pay software developers as well as web sites money for allowing their ads to be shown when people use their software or visit their sites. This inventory can be found on websites, in RSS feeds, on blogs, in instant messaging applications, in adware, in e-mails, and on other sources.

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 ad server, which responds to a site once a page is called. In most cases, ad networks deliver their content through the use of a central ad server. Besides, large ad networks include a mixture of search engines, media companies, and technology vendors.
There are three types of online advertising networks:

1. Representative (or Rep) Networks: They represent the publications in their portfolio, with full transparency for the advertiser about where their ads will run. They typically promote high quality traffic at market prices and are heavily used by brand marketers.
2. Blind Networks: These companies offer low pricing to direct marketers in exchange for those marketers relinquishing control over where their ads will run. Blind networks achieve their low pricing through large bulk buys of typically remnant inventory combined with campaign optimization and ad targeting technology.
3. Targeted Networks: Sometimes called “next generation” or “2.0” ad networks, these focus on specific targeting technologies such as behavioral or contextual. Specialize in using consumer click stream data to enhance the value of the inventory they purchase.

Finally, there are two types of advertising networks: first-tier and second-tier networks. The first one have a large number of their own advertisers and publishers, they have high quality traffic, and they serve ads and traffic to second-tier networks. Examples include the major search engines. Second-tier advertising networks may have some of their own advertisers and publishers, but their main source of revenue comes from syndicating ads from other advertising networks.