Apple speaks out on privacy rules that shook online advertising

Apple has finally explained why it started blocking some of the tools advertisers use to follow people across the web. In a blog post late on Monday, the company said the new limits target a tracking method that most users would not expect. The move caught the online ad industry off guard earlier this month, and advertisers are now bracing for the effects.

What Apple changed

The new limits run through WebKit, the browser engine behind Safari and other browsers on iPhones and iPads. Apple is blocking at the "domain level," which means it blocks whole web addresses. That way, companies cannot get around the rule by changing how they send data. Apple said blocking old-style tracking cookies is no longer enough, because the tracking industry has kept looking for new ways in.

What identity resolution means

Apple says it is going after "identity resolution." This is a way for ad companies to link scattered clues about you, such as an email address, phone number, IP address, browsing history or device details. Together, those clues let them recognize you across devices. Apple noted that people may share an email to log in or get a newsletter, but would not expect it to be passed to other companies for invisible tracking.

Who it affects

Several ad technology companies had their domains blocked without warning, including The Trade Desk, LiveRamp, ID5, Permutive and Audigent. The first rollout also stopped The Trade Desk from serving ads at all on Apple browsers. Apple fixed that a few days later. Ad professionals expect the following as more people update to iOS 27:

• Less reach, because fewer people can be targeted
• Higher prices to reach the audiences that can still be identified
• Harder control over how often someone sees the same ad
• Harder proof that a campaign actually worked

The practice is common. A September academic paper that studied 600,000 websites over 41 months found that 83.76% of them used alternative identifiers by May 2025. If ads on the open web work less well, marketers could shift money to Meta and Google, which rely on their own logged-in user data. Apple also has a growing ad business in the App Store and apps such as News and Maps.

What is still unclear

Apple has not made clear exactly how it defines an identity resolution provider. It has also shown it can add domains to its block list without notice. AdExchanger first reported that Apple has built a broader list that can dynamically block potentially hundreds of ad, marketing and data companies. Affected firms may only notice when something breaks.

What happens next

Apple points to its long-standing tracking-prevention policy. It admits that blocking can disrupt website funding, ad measurement and fraud prevention. It also says that when there is a tradeoff, it will typically put user benefits ahead of current website practices. The policy treats workarounds as seriously as security flaws and says more restrictions may come without prior notice.