Here’s a riddle. My web app keeps all of its data in a SQL database. I can spontaneously tear it down, deploy the code to a different hosting platform, and the app will still serve all the same data. Running my app in production costs $0.03 per month. How is this possible? That’s easy. You have a separate database server running somewhere that stores all of your app’s state. No, my app never talks to a remote database server.