For the second time in as many years, internet advertisers are facing unprecedented disruption to their business model thanks to a new feature in a forthcoming Apple software update.

iOS 11, the latest version of Apple’s operating system for mobile devices, will hit users’ phones and tablets on Tuesday. It will include a new default feature for the Safari web browser dubbed “intelligent tracking prevention”, which prevents certain websites from tracking users around the net, in effect blocking those annoying ads that follow you everywhere you visit.

The tracking prevention system will also arrive on Apple’s computers 25 September, as part of the High Sierra update to macOS. Safari is used by 14.9% of all internet users, according to data from StatCounter.

Six major advertising consortia have already written an open letter to Apple expressing their “deep concern” over the way the change is implemented, and asking the company to “to rethink its plan to … risk disrupting the valuable digital advertising ecosystem that funds much of today’s digital content and services”.

Tracking of users around the internet has become crucial to the inner workings of many advertising networks. By using cookies, small text files placed on a computer which were originally created to let sites mark who was logged in, advertisers can build a detailed picture of the browsing history of members of the public, and use that to more accurately profile and target adverts to the right individuals.

Many of these cookies, known as “third-party” cookies because they aren’t controlled by the site that loads them, can be blocked by browsers already. But advertisers also use “first-party” cookies, loaded by a site the user does visit but updated as they move around the net. Blocking those breaks many other aspects of the internet that users expect to work, such as the ability to log into sites using Facebook or Twitter passwords.

To tackle this, the new Safari feature uses a “machine learning model”, Apple says, to identify which first-party cookies are actually desired by users, and which are placed by advertisers. If the latter, the cookie gets blocked from third-party use after a day, and purged completely from the device after a month, drastically limiting the ability of advertisers to keep track of where on the web Safari users visit.

Facebook Twitter Pinterest ‘Ad tracking technology has become so pervasive that it is possible for ad tracking companies to recreate the majority of a person’s web browsing history,’ said Apple. Photograph: Dominic Lipinski/PA

It is this algorithmic approach which spurred the six US advertising bodies, including the Interactive Advertising Bureau and the Association of National Advertisers, to write to Apple. In their letter, published by AdWeek, the advertisers argue: “The infrastructure of the modern internet depends on consistent and generally applicable standards for cookies, so digital companies can innovate to build content, services and advertising that are personalised for users and remember their visits.

“Apple’s Safari move breaks those standards and replaces them with an amorphous set of shifting rules that will hurt the user experience and sabotage the economic model for the internet.”

Apple responded to the letter saying: “Ad tracking technology has become so pervasive that it is possible for ad tracking companies to recreate the majority of a person’s web browsing history. This information is collected without permission and is used for ad re-targeting, which is how ads follow people around the internet.”

Apple has shown little concern for advertisers’ needs in the past. In 2015, it led that year’s update for iOS with a feature that allowed widespread mobile ad blocking on the platform for the first time. The move arguably kicked off an arms race that led major media companies to increase their use of subscription models, and ceded an ever-increasing portion of the digital advertising market to Facebook and Google, two companies whose models are more resilient to adblocking than many smaller publishers.

Google has also made a move on the adblocking market, testing a built-in adblocker for its Chrome browser, which is used by 54.9% of all internet users according to StatCounter. The feature, which is expected to hit the final release of the browser sometime this year, blocks what the company calls “intrusive ads”: autoplaying video and audio, popovers which block content, or interstitial ads that take up the entire screen.



Unsurprisingly, Google’s own advertising products are not deemed intrusive.