Content blockers "affect what content is loaded" when using Safari, the default browser on iPhones and iPads. According to Apple's developer pages, the system works by allowing developers to pass a list of rules and links that can be used to block content on pages, such as images and video, text, popups, and tracking cookies.
Ad-blockers have become increasingly controversial in recent months and years. Millions of desktop users use ad-blockers -- a browser plugin that effectively scrubs every webpage from flashy, garish, and memory-consuming ads.
While these ads pay the bills to keep websites operational (including this one!), ad blockers can be used to prevent ad networks from tracking your every online move.
It's not immediately clear why the new ad-blocking privacy feature was included in iOS 9, due out later this year. After all, the iPhone and iPad maker has its own advertising network -- even if its success was limited (which is putting it nicely).
What's clear is that allowing ad-blockers in iOS 9 could deliver a serious blow to Google, the biggest rival to Apple in the mobile space, because advertising remains a massive portion of the search giant's income.
We reached out to Apple for more, but didn't hear immediately back.
For privacy and security, change these iOS 9 settings right now