Rather than stop using a service you find valuable and miss out on those adorable photos of your nephew, we think you should have tools to limit what data others can collect about you. That includes us: Mozilla does not collect data from your use of the Facebook Container extension. We only know the number of times the extension is installed or removed.
When you install this extension it will delete your Facebook cookies and log you out of Facebook. The next time you visit Facebook it will open in a new blue-colored browser tab (aka "container tab"). In that tab you can login to Facebook and use it like you normally would. 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.
Should you click on any Facebook Share buttons on other browser tabs it will load them within the Facebook container. You should know that when you're using these buttons information will be sent to Facebook about the website that you shared from.
If you use your Facebook credentials to create an account or log in using your Facebook credentials, it may not work properly and you may not be able to login. Also, because you're logged into Facebook in the container tab, embedded Facebook comments and Like buttons in tabs outside the Facebook container tab will not work. This prevents Facebook from associating information about your activity on websites outside of Facebook to your Facebook identity. So it may look different than what you are used to seeing.
There's a lot of value in your social data. It's important to regularly review your privacy settings on all sites and applications that use it. The EFF has useful advice on how to keep your data where you want it to be, under more of your control.
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.