This document provides an overview of HTML5 and CSS3 concepts for building web applications. It begins with defining what a web app is and its basic anatomy. It then covers new HTML5 structural tags, forms, multimedia capabilities like audio and video, offline data storage, geolocation, and canvas/SVG graphics. For CSS3, it discusses new selectors, the box model, positioning, fonts, visual effects, and media queries. Key topics are presented at a high level with examples to illustrate the main capabilities and uses of HTML5 and CSS3 for mobile web development.