Auren Hoffman:

In September, Apple will release new changes to Safari with iOS 11 called “Intelligent Tracking Prevention.” These changes will have large effects on the ad tech industry and create new winners and losers.
 In short, the iOS 11 changes will really help the big guys, are neutral to the small guys and significantly hurt the mid-size guys.
 A Recap
 Today, all Safari browsers essentially block third-party cookies that are dropped by domains other than the domain of the URL to which the user browsed. But the browsers reward first-party cookies with lots of privileges. This has been good for well-known sites, but also for large ad networks that get lots of clicks because a click gets routed through the ad network domain and becomes a first-party cookie.
 IOS 11 will change the concept of a “first-party cookie.” The new first-party cookie comes with a ticking clock. In the first 24 hours, the cookie acts exactly like it used to – and can be used for retargeting. So, if you go to and search for a beach vacation, you can be retargeted for that beach vacation for exactly 24 hours. It is just like Jack Bauer racing against the clock before the world explodes.
 For the first 30 days, the new first-party cookie lets you login on-site so you don’t have the annoyance of re-entering your password if you go back to the site 15 days later.
 If you have not gotten back to the site in 30 days, your first-party cookie expires.