Your app can do a lot on its own, but the moment you want to save a user’s journal entry, let them log in from any device, or share a photo, you need a place to store that information — a brain in the cloud. This chapter is about wiring your mobile app to a remote backend without building your own server. We’ll learn how to give your app a memory, a login system, and the ability to react instantly when data changes, all using a service called Firebase.