Flask takes the flexible Python programming language and provides a simple template for web development. Once imported into Python, Flask can be used to save time building web applications. An example of an application that is powered by the Flask framework is the community web page for Flask.
Flask is called a microframework because it keeps the core simple but extensible. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions. However, Flask supports extensions, that can add application features as if they were implemented in Flask itself. Extensions exist for object-relational mappers, form validation, upload handling, various open authentication technologies, and more.