Online Advertising is one of the most often cited uses and least understood uses of cookies. When cookies are referenced with respect to online advertising it is almost always in reference to their us in Behavioral Advertising where a prior behavior is maintained in a cookie for use later as a targeting criteria on a page where that behavior may currently not be demonstrated. And while this is certainly a use of cookies for online advertising it is also likely one of the least important uses in terms of overall advertising cookie use.

The use of cookies for targeting online ads is indeed growing in popularity, but by any estimation the overwhelming majority of online ads do not use cookies to achieve behavioral targeting, but they almost all use cookies for other purposes, specifically for reporting.