One of the staples of desktop web browsing may be coming to iOS with a new feature Apple is adding to Safari with a forthcoming update to its mobile operating system.
Safari on iOS 9 will include support for "Content Blocking" extensions that, when installed, will remove content from a web page based on a list created by a developer. According to Apple's sparse documentation, the functionality can be used to block "cookies, images, resources, pop-ups, and other content." In theory, that should pave the way for ad blocking browser extensions on the iPhone and iPad that users can employ to remove ads from their experience of the internet.
If that comes to pass, it could mark a big shift in the way advertisers think about mobile traffic, which continues to grow as an overall percentage of total web traffic. iOS devices are valuable targets for ads, and if users are able to block them, that could put advertisers, and hence publishers and website operators, at a significant disadvantage.
From a consumer standpoint, removing ads makes sense. They're intrusive, distracting, and often involve invasive tracking that conflicts with a desire for privacy. Ad blocking tools are among the most popular browser extensions precisely because they handle all of those nuisances in one convenient package.
A recent study from the University of Pennsylvania's Annenberg School for Communication showed that Americans don't want to give up their privacy to marketers, but feel like they don't have a choice. Ad blocking provides them with a means to get some of that control back — even if it's ham-fisted.
But blocking ads also means users are depriving publishers and other free web services of revenue they use to keep the lights on. The prevalence of ad blocking extensions like AdBlock Plus on desktop platforms has proven problematic for publishers and led to the rise of native advertisements that don't stand out as much as traditional banner ads.
Still, Apple's blocking system may hold more peril than promise for ad blocking software. At the moment, ad blockers watch a user's browsing session and employ complex rules in order to clear out advertisements. While that allows them to effectively block users from seeing advertisements, it also means that they have permission to see everything a user does on the web.
The system that Apple is implementing in Safari on iOS and OS X with its upcoming software releases works differently. Instead of allowing an extension to go through a web page and remove elements from it, a content blocking extension provides Safari with a list of content to block, which the browser applies as it loads a web page. It doesn't provide any feedback to the extension, which means that developers won't be able to track what users do.
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