Wednesday’s launch of iOS 9 introduced fully-native mobile adblocking to millions of users for the first time, and they voted with their feet. One specific ad-blocker, Peace, a $2.99/£2.29 app developed by Instapaper creator Marco Arment, is the number one paid app in the UK, US, Australia and Canada, while two others, Crystal and Purify, are in the top-ten in a number of countries.
But there’s a lot of confusion over what the blockers can and can’t do, how to enable them, and what Apple’s role is in the whole thing.
The big change in the latest version of iOS 9 is the introduction of “content-blocking extensions” in Safari, the browser that ships with the mobile operating system. But although Apple has opened the floodgates to the extensions, it hasn’t done anything directly to block ads on new iPhones.
Unless a user actively downloads a new app, such as Peace, Crystal or Purify, they will still see just the same adverts as they always had done.
Indeed, Apple has been careful not to specify which content the extensions are used to block. It doesn’t refer to its new tools as “ad” blocking, but just “content” blocking, and explains to the developers that the feature gives “extensions a fast and efficient way to block cookies, images, resources, pop-ups, and other content”.
When explaining the benefits of blocking content, Apple has focused on two specific aspects: speed, and privacy. Both are only tangentially related to adverts, instead being a function of the technology that underpins modern “programmatic” advert sales, which is how the vast majority of web ads are sold.
When a browser loads up a web page, the advertising company – such as Google, through their DoubleClick subsidiary – looks at the user, and attempts to match them to a pre-existing profile. What other sites have they visited? Where does their IP address suggest they are? What device are they using? Once it has answers to those questions, it looks through bids advertisers have made to sell ads to that particular type of user, selects the highest bid, and pushes that advert to the web page.
This all happens in the time it takes a page to load, but it can also increase the time it takes for the page to load. The code for it all must be loaded with the page, and it’s not lightweight. Many websites have multiple ad networks, as well as share buttons from social networks such as Twitter and Facebook, and their own internal analytics, all of which can add several megabytes.
Blocking some of that content can markedly speed up loading times, as well as prevent the ad network from properly identifying demographic data about the visitor. Of course, the fact that one of the ad networks is Apple’s chief competitor is a nice side effect for the company.
But the majority of content blockers available on the market position themselves firmly as advertising blockers, going further than just blocking the tracking scripts into actively seeking out the adverts themselves. That’s led to some dismay from publishers who deliberately sought out more ethical adverts, such as those from boutique ad network the Deck, only to find those have been blocked as well.
Some, such as 1Blocker, go further than simple adblocking and allow users to block other content, such as sharing buttons, custom web fonts and Disqus comments.
The technology which powers it all is firmly focused on performance. Traditional desktop adblockers work by loading a huge list of all ad servers into the computer’s memory and then running the entire content of the website through the filter, removing anything that matches. That can be comprehensive, but also incredibly resource-heavy.
By contrast, the mobile adblocking uses a small list (although “small” is relative, and word from Apple is that it caps out at 50,000 entries), which is then loaded directly into the browser. The same engine that renders the page handles the blocking, allowing it to prune adverts at the source. While developers of the old type of adblocking software initially expressed concerns that their lists wouldn’t be suitable for the new format, those fears seem to have been misplaced.
But in the long run, the format might turn out to be harder to use as a pure adblocker than it appears the moment. The other big difference between desktop adblockers and the new mobile breed is whether the list is updated in real time, and users of the iOS content blockers may find the databases are rapidly out of date.
The most aggressive advertisers could view that as a sign to start an arms race, employing increasing permutations of their server names to avoid their content being blocked. But large stable organisations will find little to gain from the diminishing returns such an approach would offer, and may be put off by its similarity to the tactics malware authors are forced to employ to bypass anti-virus software.
Whether they block ads, sharing buttons or just “content”, the blockers are here to stay.
guardian.co.uk © Guardian News & Media Limited 2010