Ad networks are companies who have large numbers of clients looking to run their banner or text ads across networks of web properties. These companies have both “advertisers” and “publishers”. Advertisers are those who want their ads to run, and publishers are web site operators who will allow space to be filled with advertising. The ad networks serve as a middle man or go-between both advertiser and publisher. Ad networks collect fees from advertisers and pay a portion of those fees to the publisher who actually serves the ads. Publishers are paid based on either how many times and ad is displayed (CPM) or clicked on (CPC). Ad networks are generally the preferred choice for web site operators who lack their own sales representatives.
Below is a list of notable advertising networks based in the United States: