Almost every website we visit nowadays requires a registration and login process. Even though browsing through a site may not require a login, as soon as we start to interact with the site, and add items to a shopping cart, for example, we need to create some sort of profile and perform a login. Corporate-based websites generally ask for a login before we can even start to interact with the site, as permissions for what you can do on the website vary depending on what your role is.

Luckily, we are able to log in to a wide range of websites using an external authentication process, such as Facebook or Google. This means that we are able to reuse a Google or Facebook login, and do not need to remember a separate username and password combination for every site.

In this section of the chapter, we will update our application to show how authentication works within Angular...