HTML5 is a language used to structure content on websites. It helps organize text, images, and multimedia using semantic tags like `<header>`, `<footer>`, `<article>`, and `<section>`. These tags make content more readable and accessible, improving navigation. HTML5 also supports multimedia elements like `<audio>` and `<video>`, which enhances interactive web experiences. It ensures content is organized, accessible, and optimized for search engines, creating a more user-friendly web experience.