While not in your snippet, it is technically required for accessibility and provides a text description if the image fails to load. Modern Adaptation and Responsiveness

Providing explicit width and height attributes (like your example’s 640x360 ) is a critical best practice. When these values are present, the browser can immediately reserve the exact space needed for the image before it even downloads. This prevents "layout shifting," where text and other elements jump around as images pop into place, significantly improving the Cumulative Layout Shift (CLS) score—a key metric for site speed and SEO. The Mechanics of the Tag

Ultimately, even though CSS handles the final look, including those initial pixel values in the HTML tag remains a foundational step for a stable, professional-feeling webpage. Do you have a you want to embed, or How to Resize an Image Using HTML - TinyMCE

This is the most vital attribute, acting as the path or URL that tells the browser where to find the image file.