What is Flask?

Flask is a lightweight, micro web framework for Python created by Armin Ronacher. It is called "micro" because it keeps the core simple and extensible — no built-in ORM, form validation, or authentication. Flask is based on the Werkzeug WSGI toolkit and Jinja2 template engine. Its philosophy is to keep simple things simple and allow developers to choose their own libraries. Flask is ideal for small to medium APIs, microservices, and projects where you want full control over your stack. It has a large ecosystem of extensions (Flask-SQLAlchemy, Flask-Login, Flask-JWT-Extended) that add functionality on demand. Flask uses a synchronous request-response model by default (WSGI), though Flask 2.0+ supports async views.