This book is aimed at developers who want to start developing highly interactive and real-time web applications such as chat systems, online multiplayer games, or want to introduce real-time updates or server push mechanisms in their existing applications. Knowledge of developing in JavaScript and web applications in general is expected. Though there is a chapter on introducing Node.js, prior knowledge of Node.js will be a plus. Readers will need access to a computer system capable of running Node.js, a test or code editor, and access to the Internet to download the required software and components.