Answer
`<source>` offers alternative media files to `<picture>`, `<audio>`, or `<video>`. • The browser chooses a source it can use. • Sources may differ by format, media query, or image width. • Provide an `<img>` fallback inside `<picture>`.
💡 Simple Example
<video controls><source src="movie.webm" type="video/webm"><source src="movie.mp4" type="video/mp4"></video>
⚡ Quick Revision
source gives the browser alternative media files to choose from.