Cookies are domain specific: a cookie from the domain guardian.co.uk cannot be read by a server form domain mail.co.uk (ah, politics and cookies). So when you buy cookie data from domain A how do you actually get your server to read it and serve an ad against it? There is a technique known as cookie synching, a fairly complex process, which enables you to map user ids from one system to another. This is how “DSPs” and ad exchanges integrate third party data with their own platforms. Vivek Vaidya does a great job of breaking this down on the Krux Digital blog.

He lifts the lid on how ad exchanges do their re-targeting and how the partnership between a data exchange (Bluekai or Exelate) and an ad exchange actually works. Vaidya provides the inner workings behind the all marketing hokum – a great education piece for a Friday morning. And it also has some visuals. Can someone tell me how to price this cookie data here in Europe? Anyone? Maybe Bluekai and Exelate can release some numbers so that traders can benchmark against? The data market could be huge but we still have no way to value it.

Re-targeting on Ad Exchanges