Facebook Container works by isolating your Facebook identity into a separate container that makes it harder for Facebook to track your visits to other websites with third-party cookies.
How does it work?
Installing this extension deletes your Facebook cookies and logs you out of Facebook. The next time you navigate to Facebook it will load in a new blue colored browser tab (the “Container”). You can log in and use Facebook normally when in the Facebook Container. If you click on a non-Facebook link or navigate to a non-Facebook website in the URL bar, these pages will load outside of the container. Clicking Facebook Share buttons on other browser tabs will load them within the Facebook Container. You should know that using these buttons passes information to Facebook about the website that you shared from.
Which website features will not function?
Because you will be logged into Facebook only in the Container, embedded Facebook comments and Like buttons in tabs outside the Facebook Container will not work. This prevents Facebook from associating information about your activity on websites outside of Facebook to your Facebook identity.
In addition, websites that allow you to create an account or log in using your Facebook credentials will generally not work properly. Because this extension is designed to separate Facebook use from use of other websites, this behavior is expected.
What does Facebook Container NOT protect against?
It is important to know that this extension doesn’t prevent Facebook from mishandling the data that it already has, or permitted others to obtain, about you. Facebook still will have access to everything that you do while you are on facebook.com, including your Facebook comments, photo uploads, likes, any data you share with Facebook connected apps, etc.