Content blocking has been a feature of the internet for a long time. Usage, and industry chatter, reached panic levels when Apple released iOS 9 in September 2015.

The question everyone is facing is simple: How does content blocking affect my business?

Turns out, when you directly measure what’s happening on websites, the answer is nowhere near simple. Let’s dig in.

Firstly, what is content blocking?

Surprisingly, there is no one definition. I like to take a very inclusive definition: Content blocking is when the user’s software or network actively blocks content from loading, or the content is modified to hide or remove content. Let’s parse this out a bit:

1. User software is the most familiar type of content blocking. Most often, it’s a browser extension/add-on, but it can be the browser itself with a built-in content blocker. Example abound: Opera browser from version 38 onwards, Brave browser, Adblock Plus, Ghostery, and many many more for all browsers and operating systems.
2. The user’s network. Corporate networks and ISPs can block content from loading sometimes. Real-life measurements show, for example, that US-based school networks have extremely high content blocking rates. Advanced consumers can configure their computer or home network to simply not connect to ad-serving domains.Moreover, consumer ISPs have announced their intention to deploy ISP-level content blocking, or are reported to be seriously considering doing so. The first ISP to deploy content blocking I’m aware of is DigiCel in Jamaica, and the mobile network Three has stated it will deploy the same technology in the UK and Italy.
3. It’s about content hiding too. Sometimes, the content blocking rules cannot block content from being loaded (there are many reasons why), so they simply hide the content. This means that although an ad may have loaded, it is not viewable and certainly won’t be clicked.

Block lists

Another important concept is that content blocking works by having lists of blocking rules.

Users can choose to subscribe to block lists that focus on different types of content: ads, analytics, malware domains, sites with aggressive ad placements, popups, and more. There are also lists that combine other lists to create one with broader blocking.

The block lists can include rules for third-party content (e.g. Google Analytics), and they can include rules that target a specific website, e.g. to hide a specific ad element on some pages on a given website. From experience helping clients, being targeted by such rules puts a business in a difficult situation they need to handle with extreme care: at the very least, site-specific block rules are a strong signal from users something is wrong with the UX.

Here is The SEM Post without ad blocking:

And here it is with ad blocking:

The impact of content blocking

Executives need to prioritize measuring two types of content blocking: Analytics blocking and, if you run ads, ad blocking.

Analytics blocking is important for all sites because pretty much every website uses an analytics package, like Google Analytics, Piwik, Sitecatalyst, or Clicky, and these are blocked by many block lists. Simply put, if your sole visibility into your traffic is a standard analytics package, you’re losing visibility to how much traffic you’re really getting, and you have no idea how content blockers actually interact with your site.

Ad blocking is important because many sites monetize their traffic using ads. How that actually affects revenue heavily depends on the website, the business, and its audience.

Other types of content that typically get blocked are social media sharing/liking buttons and chat widgets. If your website depends very heavily on social media traffic, consider looking at this type of content blocking. Likewise, if your website has a customer chat widget that’s blocked, you could be losing leads or creating a bad customer experience. I know of a UK charity that helps teenagers, and one of the channels it uses is a third-party chat widget on their website. Although this is clearly an important channel for anonymously seeking help, this chat widget is blocked by default by some popular block lists.

Lessons from directly measuring content blocking

Clearly different websites will have different concerns around content blocking, and the first step to formulating a response is to measure what’s actually going on.

To do so, I built Blockmetry to measure content blocking. Several fascinating lessons emerged over the past few months:

1. The website audience is the main factor that affects a website’s content blocking rate. Although that’s not entirely surprising, it’s a much stronger signal than I initially anticipated: Different websites catering to similar audiences (i.e. in the same niche or industry) can have very different content blocking rates.
2. Even on the same website, each section in the website has different content blocking rates. Complicating things, traffic to the website’s homepage can behave (very!) differently than the rest of the site.
3. Different days of the week have different content blocking rates, with some websites having a clear weekend/workday effect, and others not at all. The effect can be seen in ad or analytics blocking, or both.For example, the 4th of July fell on a Monday earlier this year, and in the USA, this Monday had content blocking rates akin to weekend days instead of workdays.
4. All devices (mobile, tablet, desktop) and browsers have significant content blocking rates. It’s wrong to discount, say, mobiles from your analysis because on some websites mobiles have higher content blocking rates than desktops.

Marketers and businesses need to act now

Responding to ad blockers is a complicated topic for another time.

However, specifically because of analytics blocking, you need to act now. Businesses, and specifically marketers, should worry about how their marketing efforts are being measured and how success is defined. Of note, content marketing efforts may attract different audiences, and each campaign needs to have content blocking measurement built into its metrics.

In short, you have to measure how content blocking affects your site. It’s no use depending on industry surveys or aggregate statistics, so please prioritize measuring content blocking on your website. What you’ll find is unique to your website, and you’re likely to find a few surprises.