In this chapter, we have learned how important it is to have the TLS layer or HTTPS in place for all web traffic. We have added a self-signed certificate to our sample application. I would like to reiterate that, for a production application, you must use the certificates offered by certificate signing authorities. We have also explored the fundamentals of OAuth 2.0 and various OAuth 2.0 grant flows. Different OAuth 2.0 grant flows are implemented using Spring Security and OAuth 2.0. In the next chapter, we'll implement the UI for the sample OTRS project and will explore how all the components work together.