If the thought of Facebook tracking your phone calls is creeping you out, consider the fact that the social network is also following you around the web, making note of the websites you visit, how often, and for how long. It's one of the ways that Facebook infers your interests and political persuasions even if you never express a political opinion on Facebook. As with everything else, Facebook sells that information about you for advertising purposes.

Now the Firefox browser, offered by the nonprofit Mozilla Foundation, is offering a way to stop Facebook's tracking in the form of an add-on called Facebook Container. Installing that add-on makes it much more difficult for Facebook's algorithms to track what you do online.

Here's how it works: When you install the app, it will automatically log you out of Facebook. When you log back in, Facebook will run inside a digital container that isolates it from the rest of your activity online. There may be a downside in terms of convenience: If there are sites that you sign into using your Facebook credentials, you'll need to change your sign-in method. And if you're accustomed to clicking Facebook "like" or "share" buttons on other websites (such as this one), you'll have to actually copy and paste the link into Facebook instead. But Facebook will be effectively prevented from seeing what you're doing when you're not doing it on Facebook.

Obviously, Facebook is not the only company tracking your activity online. You know this already, especially if you've ever shopped for something online, decided not to buy it, and then seen ads for whatever it was dogging you across every website you visit for the next several days. So why is Mozilla focusing its attention on Facebook alone?

As Nick Nguyen, VP of Firefox product writes in a blog post, a lot can be inferred about you from the websites you visit. That information becomes exponentially more revealing when it's combined with your social media activity. It seems clear from the Cambridge Analytica scandal among other things that Facebook can't necessarily be trusted with this kind of deeply detailed data. As Nguyen notes, the Facebook Container would not have prevented Cambridge Analytica from gaining access to personal data on 50 million or more Facebook users. Still, it seems sensible to limit Facebook's privacy intrusions whenever you can.

Besides, Firefox isn't singling Facebook out. Its Multi-Account Containers allow you to build virtual walls around different parts of your life so that, for example, if you're at a website you'd prefer your employer not to know about, you don't have to open a separate browser to check your work email account.

There's something in it for Firefox, too, of course. With the new privacy-strengthened, super-fast Firefox Quantum browser it released last year, Mozilla, once a dominant browser, is hoping to win back some of the users it lost to Google Chrome. Google deserves a privacy black eye for creating the API that allowed Facebook to track users' phone calls and texts for years without their express permission. Perhaps this is just retribution.

So if the thought of Facebook or anyone else tracking your activity on the web makes you queasy, and it probably should, consider downloading and trying out Firefox Quantum and the Facebook or Multi-Account Container. As Nguyen notes, it's impossible for most of us to know what data is being collected and when, or what the implications are of companies like Facebook having that data. Until we do, better to keep that data to ourselves.