You have now learned the fundamental aspects of the REST architectural style, the differences between an architectural style and a protocol, the relationship between REST and the HTTP protocol, and the constraints of REST. You have also learned to write some basic REST API endpoints using Express and MongoDB. A good understanding of REST and the server side of a single page application is paramount to becoming a skilled web SPA developer. In the next chapter, we will transition our focus to the frontend of SPA development, learn a few things about SPA UI frameworks and best practices, and take everything we have learned so far and apply it to the View layer.