In a recent blog post on Search Engine Land, I detailed the results of a study that examined 3rd party cookie blocking issues on the Apple iOS family of devices. The Safari browser, which is the default on the iPhone and the iPad, blocks third party cookies as its default setting, creating measurement challenges for some advertisers. In fact, we found that conversion metrics recorded by tracking systems using third party cookies could be off by 80% or more as it relates to iPhone and iPad users. Clearly, this has staggering implications for the online marketing industry. Many ad serving an audience buying solutions rely on third party cookies to target users and measure advertising response. 3rd party cookies remain the primary means of tracking users across domains, and the accelerating trend of third-party cookie blocking has ominous implications for the future of many forms of online display advertising.
While we tried to focus our conclusions on third party cookies, in the text of our study we occasionally referred to tracking solutions that rely on redirects and third party cookies interchangeably. Many advertising solutions that rely on third-party cookies also rely on redirects, however, redirects do not require the use of third party cookies. Some tracking solutions, for example, use redirects to deploy a first-party cookie from the vendor’s domain which is later read on the confirmation page of the advertiser. We’ve updated the research brief to more accurately reflect this. Special thanks to George Michie of the Rimm-Kaufman Group for pointing this out.