WTF is ad blocking?

This summer has been one big coming-out party for ad blocking. The tech, formerly solely within the domain a small percentage of power users, hit the mainstream in a big way, first with Apple’s high-profile entry into the space and then with Howard Stern’s on-air discovery of ad blockers. But while ad blocking is reaching more people (198 million globally, by last count), far fewer people know how it actually works.

Here’s a primer.

Ad blocking isn’t actually new, right? Why is this getting so much attention now?
Blame Apple. The news that the company was adding content blocking into iOS 9 struck fear, some of it probably misplaced, in the heart of publishers, who get as much as half of their of their mobile traffic from Apple’s mobile browser.

And an “ad blocker” is what, exactly?
“Ad blocker” is a catchall term for any kind of software or hardware that removes ads from a webpage. For most people, it takes the form of browser extensions such as AdBlock or Adblock Plus, which are nearly effortless to install on Google’s Chrome and Mozilla’s Firefox browsers. Some ad blocker makers have also made dedicated mobile ad blocking browsers.

Why do people use these things?
The funny thing about ad blocking is that it vastly improves the Web-browsing experience. Most modern Web pages are a mess of third-party analytics, plug-ins and advertising tags, which together weigh down publishers’ pages. Ad blocking prevents all of those elements from loading, which not only speeds up page load times but also cuts back on the number of things vying for readers’ attention. There are also privacy benefits to running ad blockers, as the software also prevents third-party tracking tags from loading and following people across sites.

In other words, for the user, there’s almost no downside to running an ad blocker.

So how does ad blocking actually work? How do blockers know what’s an ad?
Ironically, ad blocking software is pretty “dumb” in the sense that it doesn’t block anything by default. Instead, it looks to massive “filter lists,” the most popular of which being Easy List, which contain thousands of page elements (such as ad serving domains) that are associated with ads. Because the vast majority of ads are served through ad exchanges or ad networks, blocking them is rarely more complicated than blocking the domains of the ad servers themselves. Ad blockers can target not only display ads but video ads and sponsored content widgets from Taboola and Outbrain as well. Even so-called “native ads can fall victim to it.

how-adblock-plus-works copy

This must drive brands and agencies nuts.
So far, ironically, it doesn’t seem to be on their radar. That could change though as ad blocking approaches critical mass.

So how does this hurt publishers?
It’s pretty simple: Publishers don’t get paid for ads that don’t get served. Blocked ads are lost revenue. And while that might not have been a big deal when only a handful of people were running ad blockers, it’s a much bigger problem now that millions of people are doing so.

Are publishers fighting back?
They’re trying to, anyway. Publishers’ anti-ad blocking measures come in a handful of forms. On the softer side, some publishers ask readers to “whitelist” their sites, i.e., telling ad blockers to let their ads run. Others are taking a harder approach by preventing users of ad blockers from accessing their content entirely. Another tactic, fueled largely by anti-ad block vendors such as PageFair, Secret Media and Sourcepoint, is to circumvent ad blockers and serve ads anyway. Secret Media, for example, does this by encrypting ad server data, making it much harder for ad blockers to target it.


Will any of that actually work?
The conventional wisdom these days is no, not really. While publishers who try to fight ad blockers might win out in the short term, in the long run, it’s likely that the ad blocking crowd will find a way to workaround the industry’s defenses. The EasyList and AdBlock Plus forums, for example, are full of users sharing notes on new ad serving methods, and recommendations on how to block them.

“The community behind ad blocking is incredibly reactive, said Secret Media founder Frédéric Montagnon. “If you use a new element, they will spot it and find a way to block it within hours.”

Photo: Shutterstock