This document provides an overview of HTML5 and its capabilities for building interactive web applications. It discusses the history and development of HTML5, including the roles of the WHATWG and W3C. It also summarizes key HTML5 features such as JavaScript, Canvas, WebSockets, storage options, and emerging 3D capabilities. Throughout, it provides examples of how these features can be used to create games, multimedia experiences, and real-time applications on the modern web.