Image Alt Text: Match the Words to the Image’s Job

A book cover appears on three pages of a creator’s website. On one page, it illustrates a discussion of the design. On another, selecting it opens a sample. On a third, it sits inside a link beside the words “Download the sample PDF”. The artwork is identical, but its job has changed.

That difference should shape the text alternative. Before asking an AI assistant to describe an image, tell it why the image is there, what surrounds it and whether selecting it does anything. A vivid description can still leave the reader without the information needed for the next step.

Start with the image’s job on this page

The W3C Web Accessibility Initiative’s guidance on informative images says that a text alternative should convey the image’s relevant meaning or content. A literal inventory is not always the most useful choice. The author’s reason for including the image helps determine what needs to be conveyed.

For a creator reviewing a publication, that calls for an editorial decision before a wording exercise. Is the cover identifying a book, supporting an argument about its composition or serving as a route to another page? Write that purpose in a short sentence first.

Consider a fictional guide called “Field Sketches”. Its cover shows a gold leaf outline against a navy background. The examples below are invented publishing situations, not an accessibility audit of a real website. They apply W3C’s guidance to a small creator workflow.

When the picture supplies information

In a design discussion, suppose the article compares the gold leaf outline with the darker background. If that visual relationship is not already conveyed in the text, a proposed alternative could be: “Field Sketches cover, with a gold leaf outline against a navy background.”

The description earns its place because those details support the surrounding discussion. A longer account of every mark, texture and decorative flourish would need a reason. Equally, simply naming the book might omit the particular design feature the article asks the reader to consider.

This is not a universal description for that file. It is a proposed wording for the stated use. If the discussion changes to lettering, the relevant detail changes too. Review the image in its final context rather than approving its alternative in isolation.

When the picture is the link

Now suppose the cover is the only content of a link that opens the guide’s sample PDF. The W3C tutorial on functional images advises that the alternative communicate the action or purpose, rather than merely describe the picture.

For this fictional link, I would propose “Open the Field Sketches sample PDF”. The wording identifies the destination’s purpose and format. A description of the gold leaf would leave the action unexplained.

Check the destination before choosing the verb. If selecting the cover opens a product page, the alternative should identify that destination instead. Do not label a link as a sample download because the creator hopes to offer one later. The wording needs to match what the published link actually does.

When the link already has sufficient text

For the third use, imagine one link containing both the cover and the visible text “Download the Field Sketches sample PDF”. The image adds no further information about the action.

W3C’s decorative-images guidance includes images that supplement text within the same link without adding information. In that situation, an empty alternative, alt="", avoids repeating the already supplied meaning. Omitting the attribute altogether is a different choice; the guidance notes that some screen readers may announce the file name when it is absent.

The same-link condition matters. Nearby text is not automatically part of the image’s link. Ask the implementer to check the actual structure before applying the example. Do not empty the alternative on an image-only link and assume a caption elsewhere will necessarily supply its purpose.

Give an assistant the context it needs

A useful drafting brief includes four things: the image, its purpose, the nearby wording and the action attached to it. For example: “This fictional cover is the only content of a link opening the sample PDF. Draft a concise text alternative that identifies the action and document. Do not invent visual details or a different destination.”

For an informative use, change the brief accordingly: identify the visual feature that matters to the discussion and state what the surrounding paragraph already explains. Ask the assistant to flag any detail it cannot establish from the supplied material.

The draft remains a proposal. A tool receiving only a filename and a title has not been given enough evidence to describe a leaf, a person or a diagram. Review the actual image and page before accepting wording that sounds confident.

Keep a small placement record

For reused artwork, I would keep a short record with one entry per placement:

• The page or content item where the image appears.
• Its purpose in that location.
• Any link destination and visible text within the same link.
• The approved alternative, including an intentional empty value where appropriate.
• The version reviewed and the person responsible.

This is a proposed handover method, not a requirement to maintain a separate spreadsheet for every image. Its point is to prevent a description approved for one placement from silently becoming the answer for every later use.

If your publishing workflow reuses stored media text, check the result in each placement. Do not assume that changing a file-level description will produce the intended wording everywhere. The article does not claim a particular content-management system behaves one way or another; verify the workflow you actually use.

Review the reader’s next step

A final review should look beyond whether the alternative field contains words. Ask whether the reader can obtain the information the picture contributes, identify the link’s purpose and understand what selecting it will do.

Review the published structure with appropriate accessibility checks, including assistive-technology review where available. No screen-reader or website test was performed for these fictional examples. A plausible alternative by itself is not evidence that the whole page is accessible.

Creators preparing reading material can also use MaryChuks’ guide to keeping ebook values connected to their headings. The formats differ, but the editorial concern is related: preserve the relationship that gives an item its meaning.

Return to the three cover placements. One needs relevant visual information, one needs an action and one may already have sufficient link text. Begin with that difference. Then make the alternative serve the reader’s purpose at the place where the image is actually used.

Sources

• W3C WAI: Informative Images, updated 17 June 2019.
• W3C WAI: Functional Images, updated 12 April 2017.
• W3C WAI: Decorative Images, updated 27 July 2019. All three primary guidance pages checked 30 October 2026; used as established guidance, not a new announcement.