Oh no, it's time to add security! Ahhh!
Wait, come back! Security in Symfony is awesome! Seriously, between things called "voters" and the Guard authentication system, you can do anything you want inside of Symfony, and the code to do it is simple and expressive.
Security has two sides: authentication (who are you?) and authorization (do you have access to do X). We'll talk about each of these, creating an traditional form login system and and API token authentication. Then, we'll turn to authorization, with roles, voters and other good stuff:
... and how to create a back door into your... spaceship... that will allow it to be destroyed with one careful shot. Just kidding! Let's make some secure sites / spaceships!