This chapter was pretty intense! We had an overview of relational and NoSQL databases, we learned about MongoDB and MongoEngine, SQLite and SQLAlchemy, and how to use extensions to integrate Flask with each. Knowledge is stacking up fast! You're now capable of creating more complex web applications with database support, custom validation, CSRF protection, and user communication.

In the next chapter, we'll learn about REST, its advantages, and how to create services to be consumed by your app.