title: How to do a costum authentication with firebase, angular and node?
body: <p>So I'm making a transition to firebase with my mean application.</p>
  <p>But I'm getting lost in all the information on de website of firebase on how to authenticate an user.
  I can allready create users on firebase and I have a node project.</p>
  <p>So my questions are:</p>
  <p>how do I need to do the login part?</p>
  <p>Do I need to call firebase.auth().signInWithEmailAndPassword() in my angular application?</p>
  <p>Do I need to call my node application and to there the autentication?</p>
  <p>How do I check if a user is signed in ?</p>
  <p>If you guys know a good read-up, i'm very interested</p>