Flask is a lightweight and powerful web framework written in Python, often utilized for developing web applications. Coursera's Flask skill catalogue teaches you the core functionalities of this micro web framework, showcasing its simplicity and flexibility. You'll learn about routing URLs for building web page links, utilizing templates to build a user-friendly interface, and integrating with databases for data persistence. Furthermore, you will understand how to implement session tracking, utilize security features such as user login and authentication, and leverage Flask's extensions to augment your web applications. Whether you're a budding web developer or a seasoned programmer looking to pick up a new framework, mastering Flask will equip you to create dynamic, data-driven websites efficiently.