In the last module, I introduced the existing application and briefly talked about the hows and whys of its structure.

The app is an example of what you might encounter in an enterprise-level organization: it's a fully functional React application, but it's outdated. Even though it's using the Create React App framework (designed to make it easy to take advantage of improvements to React), it has not kept up with the new releases as they've come along — the most obvious one being React Hooks.