Image SEO
Short answer
Google finds images in the src attribute of img elements and does not index CSS images. Alt text should be descriptive and in context, not stuffed with keywords; Google reads it alongside computer vision and the page content. High-quality images and video still matter for Google's AI features.
Use HTML image elements
Section titled “Use HTML image elements”<!-- Indexed --><img src="robots-txt-flow.png" alt="Flowchart: crawler requests robots.txt before other URLs">
<!-- Not indexed as an image --><div style="background-image: url(robots-txt-flow.png)"></div>Write useful alt text
Section titled “Write useful alt text”Alt text also serves people using screen readers. It acts as anchor text when an image is a link.
Images and AI features
Section titled “Images and AI features”How this wiki does it
Section titled “How this wiki does it”The wiki has few images by design. Its share images are referenced with og:image and carry alt text via og:image:alt.