HTML5 provides many new features for building rich and engaging web applications, including improved multimedia, graphics, and offline capabilities. It defines new semantic elements like <header>, <nav>, <article>, and <aside> that help structure and outline pages. HTML5 also introduces form input types for color picking, date/time selection, email, URL and more. Additional APIs allow creation of offline web applications using the Cache Manifest, storing persistent data locally with Web Storage, and manipulating browser history. HTML5 brings powerful new capabilities for embedding video, using <canvas> for drawing, and 3D graphics with WebGL.