Ginny Marvin:

In June, Apple introduced Intelligent Tracking Prevention, an initiative aimed at limiting third-party trackers from capturing cross-site browsing data, in the next version of Safari, coming out this fall. The move has implications for ad performance tracking for Google and others. On Thursday, Google sent an email to AdWords advertisers outlining changes it is making in response to Intelligent Tracking Prevention.
 
 What is Intelligent Tracking Prevention?
 
 In short, with ITP, third-party cookies that are determined to be able to track users across sites can only be used for 24 hours from the time a user visits a website via Safari. After 24 hours, the third-party cookies can only be used for log-in purposes. The cookies are purged entirely after 30 days.