Alt text, title, caption, description: which image fields matter for SEO?

Where each field goes

The attachment details screen has four text fields. They are stored differently and appear in different places.

The Title deserves a note because it is the field people fill in most carefully. WordPress sets it automatically at upload, from the file name, or from a title embedded in the file's metadata if there is one. It helps you search the Media Library. It is not the HTML title attribute; the block editor has a separate "Title attribute" field under an image's Advanced settings for that, empty by default.

The Description is only shown on attachment pages. New WordPress sites have had attachment pages switched off since version 6.4, so on those sites the field is never displayed anywhere.

What Google says it uses

Google's image SEO documentation names the signals it draws on to understand an image:

• Alt text, which it calls the most important attribute for providing image metadata, used together with its own image analysis and the page's content.
• The content of the page around the image, including captions and image titles.
• The file name, as a light clue to the subject.
• Structured data and the page title for how a result is presented.

So in WordPress terms: alt text first, then a descriptive file name set before upload, then a visible caption and relevant surrounding text. Everything in that list is something a visitor or a crawler can actually see in the delivered page. The Media Library title and description usually are not.

Writing each field well

Alternative Text. Describe what the image shows, in the context of the page, in a short phrase or sentence.

• Weak: grinder
• Stuffed: best burr coffee grinder buy cheap grinder espresso
• Good: Hand burr grinder with its hopper removed, showing the conical burrs

Leave it empty for purely decorative images so screen readers skip them. Do not start with "Image of".

Caption. Use one when it adds something a reader wants: a credit, a place, a detail not obvious from the picture. Captions are among the most-read text on a page. Not every image needs one, and repeating the alt text as a caption helps nobody.

File name. Rename before uploading: conical-burr-grinder-disassembled.jpg, not IMG_4471.jpg. WordPress cleans up spaces and special characters but keeps the name you give it, and the name becomes part of the image URL permanently.

Title. Tidy it if you rely on Media Library search. Otherwise leave it.

Description. Skip it unless you publish attachment pages on purpose, for instance a photography portfolio.

The title attribute, separately

The HTML title attribute on an image produces a tooltip on desktop hover. It is not read reliably by screen readers, it is invisible on touch devices, and Google's documentation gives it no special role beyond being text on the page. It is optional.

If you want one, Hydrogen SEO's Add Missing TITLE Attributes setting can fill it at render time alongside missing alt attributes, using formats you set; see image SEO attributes. Treat it as a nicety. The alt attribute is the one to get right.

A five-minute image routine

1. Rename the file descriptively before upload.
2. Upload, and fill in Alternative Text straight away.
3. Insert the image; adjust the alt text in the block if this page needs different wording.
4. Add a caption only if it informs.
5. Place the image near the text it relates to.

Then check a finished page with the image alt checker. It lists every image with its alt state, which is quicker than reading the source.

If your site still has attachment pages enabled, each image also has a thin page of its own built from the title and description. Redirecting them to the file or parent post is covered in redirecting attachment pages.