Use case, how detestable the term is. Remember all those awful papers you had to write in school for use cases of someone selling widgets in candy land? Thankfully, this is a book about code, and code is always useful, and always has a use case; even the Hello World application has a practical application! (Say that five times fast, I dare you.)

For this use case chapter, our goal is to really show you how to do something very useful that comprises of more than just a couple lines of code. We'll be focusing on the steps to get things done, and start moving at a slightly faster pace, after all, you should know how to get to Setup by now. This chapter will have many moving parts, as we are building a full-blown app and not just writing standalone controllers, extensions, methods, pages, or triggers; though we will be using all of them in turn.

Since this chapter involves using an external system, we want to highlight the importance of Terms...