This document provides an overview of real-time web servers and the Tornado framework. Tornado is an open-source, non-blocking web server that uses epoll to handle thousands of simultaneous connections efficiently. It supports features like push technologies and asynchronous requests to update clients in real-time. The document describes Tornado's modules for building web applications, shows code snippets for URL mapping, handling POST arguments, and using templates, and discusses asynchronous requests and UI modules.