In this chapter, we have learnt how to allow users to log in using the traditional username and password method and also through their social networks. We explained the difference between authentication and authorization. Authentication dictates if a user can log in or not into the system, while authorization defines what a user is allowed to do or see while he/she are logged into the system.

This chapter is very important, and it will enable us to add more interesting features such as product checkout, order creation, and history by user. Read on, that's what we are doing next!