1. Computer Skills

Content Blocking on OS X

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Read Time: 6 min

Content blocking, also known as ad blocking, has been getting more and more press recently. Apple recently brought content blocking to iDevices in iOS 9 and publishers have been complaining that it is starting to have a significant affect on their revenues.

The two most common kinds of blocked content are ads and trackers. There are plenty of reasons you might want to block both, although there are some ethical considerations. 

In this tutorial, I’ll explain what content blocking is, why you might like to do it and how to set it up on a Mac.

Content Blocking Explained

Content blocking is the act of preventing publishers from serving specific pieces of content to a computer when you visit their site. 

A browser plugin can prevent the targeted content from ever loading. Although in theory any kind of content can be targeted, the two most common kinds that are blocked are ads and trackers.

The Problem

Online Ads

Online advertising has become a bit ridiculous. In an effort to generate as much revenue as possible, some sites serve upwards of ten or fifteen ads on every page. 

Every one of these ads needs to be loaded by the user’s computer. Unless you’re on a fast Internet connection and using a powerful computer this will cause a noticeable slow down in page load times.

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The front page of iMore without an adblocker running.

Even in cases where there aren’t too many ads, they can be used to deliver malicious content to visitors of the site. Often it is not the publisher but the ad network who is behind this kind of attack. 

Even major sites aren’t safe. Forbes was recently hit with an attack like this, ironically after preventing users with ad blockers from visiting their site.

Online Trackers

The other type of content that is commonly blocked is trackers. These are pieces of code that get embedded in your browser and track your online habits. 

Trackers can record what sites you visit, how often you do it, your location and a whole lot more. In general, they aren’t actually malicious just spooky; they’re used to serve targeted ads rather than kidnap you. 

For example, if you visit Amazon and check out a specific product, you’ll often see ads for that product in the sidebar of other sites.

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The front page of iMore with the ads blocked.

Ethical Issues

There are some ethical issues with content blocking. By preventing ads from loading you deprive publishers of the revenue they would otherwise have earned. 

While the revenue-per-visitor is often tiny, if everyone started blocking ads then most ad supported websites would collapse. 

Some people liken ad-blocking to torrenting or stealing but that is probably stretching things a bit far. 

Regardless, if you’re going to start using an ad-blocker it is worth considering the implications of you doing so. You may be costing your favourite websites money.

Blocking trackers is a little more ethically defensible. 

Although it may affect publishers' revenues, because they cannot serve targeted ads, it won’t do the same degree as fully blocking all ads. 

Also, tracking your actions on other sites could be considered an extreme privacy violation. Blocking trackers is just balancing the books a little.

Setting Up Content Blockers on a Mac

To block both ads and trackers you only need two pieces of software: 

  • Adblock Plus, and 
  • Ghostery

While on iOS content blockers need to be installed at a system level, on OS X—where they’ve been around a lot longer—they’re available as browser plugins. 

As long as you’re using a recent version of a major browser, it should support plugins.

Blocking Ads With Adblock Plus

There are quite a few ad-blockers out there but I’d recommend Adblock Plus.

Adblock Plus is one of the most popular ad-block plugins available. It works with the four major OS X browsers—Safari, Google Chrome, Firefox and Opera. It’s also completely free and open source. 

Browser plugins can gain quite a lot of control over your Internet and less scrupulous developers have inserted their own ads or stolen user data before; it’s nice to know that the code is available for anyone to inspect.

By default Adblock Plus blocks all ads from loading, including those on social networks and video sites, but you can add sites you want to support to a whitelist. 

If you love Envato Tuts+ content, I’d recommend adding us.

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Adblock Plus is simple to install.

To install Adblock Plus, visit the developer’s website and select the browser you want to install it on. Click the Install for [Browser] button and the plugin will be downloaded and added to your browser.

Once it’s installed, Adblock Plus will run automatically.

If you regularly use more than one browser, ensure you install Adblock Plus on both.

Blocking Trackers With Ghostery

While Adblock Plus blocks some trackers just by virtue of blocking ads, it doesn’t do as complete a job as Ghostery. Similarly, there are alternatives tracker blockers out there but none are as powerful as Ghostery.

Ghostery works with Safari, Google Chrome, Firefox and Opera. Unlike Adblock Plus, however, it isn’t open source. 

While it’s free for consumers to use, Ghostery collects information on what trackers users encounter and sells it to advertising industry groups, universities and the press so that they can all study online advertising.

 Ghostery works with all major OS X browsers.

Ghostery maintains a database of trackers. It automatically blocks any, that are in the database, from loading when you visit a site. 

Again, if there is a site you’d like to support you can add them to a whitelist but there is less need to do so with Ghostery than with an adblocker.

How to Install Ghostery

Visit the consumer section of the Ghostery website. The site uses browser size to determine whether to offer the mobile or desktop plugins so make sure your browser is full screen. 

Select the browser you are using and click the Add to [Your Browser] link. You’ll be taken to the relevant web store and you can install the plugin from there.

With that done, Ghostery will run automatically.

Once again, if you use more than one browser, ensure you install it in all of them.


There are plenty of reasons to block online content like ads and trackers. Doing it on a Mac is simple by installing Adblock Plus and Ghostery on each browser. With them both running, all ads and trackers will be prevented from loading whenever you visit a website.

Blocking ads and trackers does affect publishers ability to earn a living. If you love a specific website, such as Envato Tuts+, you should add them to a whitelist.

With Adblock Plus and Ghostery running your browsing will be a lot faster, more private and safer. If you’ve any issues setting things up, let me know in the comments.

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