Alt text is a short written description attached to an image in your website's code. When an image has none, anyone or anything that can't see the picture directly—a blind visitor using a screen reader, or a search engine cataloguing your site—has no idea what it shows.
Why it matters
Visitors who use screen readers hear only the word "image" where a described picture should be, so they miss information or context you meant to give them. Search engines can't index images they can't read, so those images won't show up in image search results. In some regions, missing alt text can also count as a legal accessibility failure.
How to fix it
Add a short, specific description to each meaningful image. In HTML, this is the alt attribute:
<img src="golden-retriever-puppy.jpg" alt="Golden retriever puppy sitting on grass">
Describe what the image shows, not "photo of" or the file name. For images that are purely decorative and carry no meaning, use an empty alt so screen readers skip them:
<img src="divider-line.png" alt="">
WordPress
Open Media Library, click an image, and fill in the Alt Text field. When adding an image inside a page or post with the block editor, select the image and enter the description under Settings → Alt text.
Squarespace / Wix / Shopify
Click the image in the editor and look for an Alt text, Alternative text, or Description field in the image settings panel, then save.
Hand-coded HTML
Edit each <img> tag directly and add the alt attribute as shown above.
How to check it worked
View the page, right-click an image, choose Inspect, and confirm the <img> tag now has a meaningful alt value—or hover with a screen reader on and listen for the description instead of just "image."