HTML5 introduces several key changes and features over previous versions, including:
1. New Elements: <article>, <section>, <nav>, <header>, <footer>, <aside>, and others forbetter semantic structure.
2. Multimedia Support: Native support for video and audio with the <video> and <audio> elements, reducing reliance on plugins like Flash.
3. Canvas and SVG: The <canvas> element for drawing graphics and the support for scalable vector graphics (SVG).
4. Local Storage: Web Storage API for storing data on the client side, allowing for offline support and faster load times.
5. Improved Forms: New form input types (e.g., email, date, range) and attributes (e.g., placeholder, autofocus) for better user experiences.