Authentication Tokens
When working with "Authentication Tokens", these tokens are typically created in the "JSON Web Token" Format (JWT).
As explained in the previous lecture, those "tokens" are really just long strings which are constructed by an algorithm that encodes data into a string (with help of a private key, only known by the server).
You can learn more about JSON Web Tokens (JWTs) here: https://jwt.io/
In the end what matters most to us here is the ID token, which is this authentication token, this long string with all that encoded data
that was generated by the Firebase server, and that can only be verified by the Firebase server therefore.
