Flask is a micro framework for Python written by Armin Ronacher in the year 2010. What does micro mean?
Micro simply means that Flask is small. It doesn’t come with a particular set of tools or libraries that other popular Python frameworks like Django or Pyramid provide. Flask is designed with extensibility in mind. It only provides a core set of features and relies on extensions to do the rest. Right out of the box Flask doesn’t provide any support for accessing the database, form validation, authentication, file uploads and so on. To add these functions to your application you have to use extensions. Because you can choose the extensions you want, you end up with lean stack without any extra cruft.
Flask is also less rigid about how you should structure your application. Unlike framework like Django, where you have to follow the strict rules. In Flask, you are free to structure your application the way you want.
In the next lesson, we will learn how to install Flask.
Note: Exercise files for this tutorial is available at https://github.com/overiq/flask_app.