How do I connect to Facebook and why should I do that?

To connect to Facebook, tap the Facebook connect button on the game’s home screen. You can also connect from the Settings menu, which opens from the cogwheel button. If you wish to disconnect the game, this can also be done from the Settings menu.

When you’re connected to Facebook, your progress will be backed up to cloud so that you can then sync your progress to another device or restore the progress in case you need to uninstall and reinstall.