Flask is a web framework for Python. It provides functionality for building web applications, including managing HTTP requests and rendering templates.

Flask is a back-end framework. It’s actually a micro-framework so won’t find things like form validation or a database abstraction layer. Django is the way to go for a more complete framework.

The Flask server binds to port 5000 by default.

Flask is a micro web framework powered by Python.

Docs

https://realpython.com/introduction-to-flask-part-1-setting-up-a-static-site/

Install

$ sudo pip install flask

Verify installed successfully:

$ pip list
Package                                Version 
-------------------------------------- --------
Flask                                  1.1.2 

To install flask for Python3.4:

# pip3 install flask
...
# pip3 list
Flask (1.1.2)
...
# which flask
/usr/local/bin/flask

Resources

The Flask Mega Tutorial - The most well-known tutorial for learning the Flask web framework.

Building a Python App in Flask