title: How to store user data with node/Express
body: <p>I am working on my first Node/Express-application and I was able to create
  a functioning app with user authentication.
  But what I don't understand is, how to connect a user to its stuff (e.g. the settings) that he/she has made after the login and how/where to save it?<br>
  So in case, another user is logged in, that he/she gets their selected device with the settings that they made. </p>
  
  <p>My goal of the app is to control sensors on a raspberry, like to set them on and off or take photo's from a connected webcam.
  So can someone explain how to handle the data/setting etc. from a user?</p>
  
  <p>I am sorry if this is a stupid question. But I am new this, like to understand what I am doing and before, I have only done HTML (S)CSS and simple JS, where I didn't have to worry about the backend part. </p>