Here’s what advertisers need to know about the new feature and how it could affect their ability to target ads to consumers.
What is it?
As its name suggests, Intelligent Tracking Prevention is an anti-tracking feature that is designed to protect user privacy. Specifically, it “reduces cross-site tracking by further limiting cookies and other website data.”
How does it work?
Intelligent Tracking Prevention looks at the resources web pages load as well as how users interact with those pages. Interactions captured include taps, clicks, and text entries.
The data Intelligent Tracking Prevention collects is put into buckets for each top-level domain (TLD) or TLD+1. It is then run through a machine learning model to determine whether the domain in question is capable of cross-site tracking.
Apple WebKit engineer John Wilander explained:
Out of the various statistics collected, three vectors turned out to have strong signal for classification based on current tracking practices: subresource under number of unique domains, sub frame under number of unique domains, and number of unique domains redirected to.
What does it do?
Once Intelligent Tracking Prevention detects cross-site tracking, it takes action to either keep or purge first-party cookies and website data based on a number of factors.
For example, for the TLD example.com, if a user has not interacted with the website for 30 days, Intelligent Tracking Prevention will purge its cookies and website data. On the other hand, if the user does interact with the example.com website, it will allow its cookies to be used in a third-party context for 24 hours.
According to Wilander, “This means users only have long-term persistent cookies and website data from the sites they actually interact with and tracking data is removed proactively as they browse the web.”
To ensure that users can stay logged into websites, partitioned cookie functionality has been added to WebKit. This allows for a website to keep its cookies beyond 24 hours for the purpose of keeping users signed in but not for cross-site tracking.
Why is the ad industry so upset?
The current version of Safari already blocks third-party cookies but as the ad industry sees it, the potential blocking of first-party cookies goes way too far.
Six industry groups, including the Interactive Advertising Bureau, American Advertising Federation, the Association of National Advertisers, and the 4A’s, penned an open letter to Apple “from the Digital Advertising Community.”
In it, the groups argue that “Safari’s new ‘Intelligent Tracking Prevention’ would change the rules by which cookies are set and recognized by browsers”, in turn disrupting the infrastructure of the digital economy. The letter explains that “Blocking cookies in this manner will drive a wedge between brands and their customers, and it will make advertising more generic and less timely and useful.”
In practical terms, Intelligent Tracking Prevention will severely disrupt behavioral targeting and retargeting. While these forms of targeting are very popular with advertisers because of their efficacy, they are frequently the source of complaints from consumers and privacy advocates.
How has Apple responded?
Those user complaints seem to carry a lot of weight with Apple, which is refusing to give in to the ad industry’s demands to rethink Intelligent Tracking Prevention.
“Apple believes that people have a right to privacy – Safari was the first browser to block third-party cookies by default and Intelligent Tracking Prevention is a more advanced method for protecting user privacy,” the company stated. “The feature does not block ads or interfere with legitimate tracking on the sites that people actually click on and visit. Cookies for sites that you interact with function as designed, and ads placed by web publishers will appear normally.”
How is the ad industry likely to respond?
Of course, advertisers are unlikely to resign themselves to a new world in which cross-site tracking is difficult if not impossible in the most popular mobile browser.
As privacy expert Alexander Hanff noted, Intelligent Tracking Prevention can’t thwart server-side tracking and now that Apple is taking aim at client-based cross-site tracking, “it is highly probable that Apple’s new approach to tracking will only accelerate a move to these server side technologies from those who have yet to use them.”
So even if Apple’s move causes a lot of hand-waving, given the importance of cross-site tracking to the online advertising ecosystem, this almost certainly won’t be the end of the story.