Firefox Nightly is the new Mozilla browser for Android devices. It's based on Android Components and GeckoView, the Android version of the Quantum Firefox motor. Its main goal in the long run? to become the default browser for the company with the emblematic fox and replace the traditional Mozilla Firefox.
To talk about Firefox Nightly is, without a doubt, to talk about the new concept of 'sessions'. These sessions are basically subgroup of tabs that you can save and store on the browser's homepage, which you can then access with a single touch of a button. Every time you exit the browser, your opened tabs will be stored in a new session. That way, when you open the browser again, instead of having all the tabs open, you'll only see one homepage where you can open any of your old sessions... or create a new one.
Other than the 'sessions', Firefox Nightly includes all the features that you'd expect from a modern browser. You can easily open an incognito tab, scan QR codes directly from your browser, manage and synchronize your markers with your Mozilla account, activate the desktop mode on any tab, change the default web browser, etc.
Firefox Nightly is an excellent browser for Android that includes a bunch of features as well as a simple and sleek interface. In addition, the 'sessions' system takes up less RAM memory than other browsers for Android, which a lot of users will be incredibly thankful for.