Major online networks deliver targeted ads to consumers and provide tracking and reporting of impressions or on-page views in ways not possible with traditional media.

There are three main types of online advertising networks:

Vertical Networks – These networks offer full transparency about where an advertisement will appear. Vertical networks typically promote high-quality traffic at market prices and are heavily used by major brands.

Blind Networks – Blind networks offer good pricing. In exchange, marketers generally relinquish control over where their advertisements will appear. Some networks will offer an “opt-out” method to avoid appearing on certain sites.

Targeted Networks – Targeted networks specialize in using consumer clickstream data to enhance the value of the inventory they purchase. Increasingly, targeted networks are including social graph data collected via consumers’ opt-in activity on their preferred social networks.

The network with the greatest reach is Google Adwords, which allows businesses to advertise and target just the people they would like to reach. Adwords appear as a column of sponsored links just to the right of Google’s search results