Tornado is a Python web framework and asynchronous networking library that is designed for handling real-time web applications. It is a fast, scalable, and non-blocking web server that can handle thousands of simultaneous connections. Tornado is known for its high performance and it is used by some of the most popular websites and applications such as FriendFeed, Facebook's Tornado-based Chat application, and Bitly.

Tornado is built on top of the Python's asyncio library, which provides a powerful foundation for building scalable and high-performance network applications. It is designed to handle the heavy load of real-time web applications and is well-suited for building WebSockets-based applications. Tornado's event-driven architecture allows it to handle multiple requests concurrently, making it ideal for handling large volumes of traffic and long-polling scenarios.

Tornado is an open-source project that is maintained by the Python community. It is licensed under the Apache 2.0 license, which means that it can be used for both commercial and non-commercial projects. Tornado is easy to learn and has a large and supportive community that provides extensive documentation and helpful resources for developers.