You can save your progress through Facebook, Google Play, Game Center, or iCloud.
Important: Be aware that if you disconnect your Facebook or Google Play account from in-game Settings, you will lose access to your original account! We are required to relinquish all ties to your Facebook and Google Play data if you willingly log out from the game.
While this is a good way to go if you want to start completely from scratch, you will not be able to return to your original account, should you ever want to.
Facebook, Game Center, and Google Play save your progress by connecting your ID to the account in our database. Your account is always available to you by logging in after a re-install or on a new device.
iCloud (as opposed to FB, GP, and GC) stores your progress only through iCloud Drive and therefore it's important to always have iCloud Drive saving allowed in your device Settings, otherwise the progress can't be saved and loaded. Please be aware that we are not responsible for any external iCloud Drive issues which could resolve in iCloud incorrectly loading your data.
Remember, it's impossible to play on two devices at the same time.