Start with the image’s job
Alternative text, often called alt text, is a text alternative for an image. It can be read by assistive technology and may appear when an image does not load. Its purpose is not to describe every visible detail. It should give someone who cannot see the image the information they need to understand or use the page.
Before writing, ask: Why is this image here? A photo on a staff page might identify a person; an illustration beside instructions might show where to find a control. The same image can need different alt text in different places. A photo of volunteers sorting supplies might call for “Volunteers sort donated coats by size” on a page about how donations are handled. On a page where the photo simply adds atmosphere and the nearby text already explains the activity, it may not need a description at all.
Describe meaning, not everything in the frame
For an informative image, write a concise description of what matters to the surrounding content. Use specific, ordinary words. “A ramp leads to the library’s main entrance” is more useful on a visitor information page than “Building exterior.” Unless the image format itself matters, there is usually no need to begin with “Image of” or “Photo of”; the technology presenting the alt text can already convey that it is an image.
Keep interpretation separate from what the image shows. “Three people sit around a table reviewing a floor plan” describes visible information; “A successful team plans its next project” assumes an outcome the picture cannot establish. Details such as clothing, color or background belong in the alt text when they help explain the point of the image, not simply because they are present. Avoid adding promotional phrases or search keywords that do not help a reader.
Handle decorative, linked and complex images differently
Some images contribute no information beyond the nearby text. A decorative wave between sections, for example, should generally have empty alt text, written in HTML as alt="", rather than a description such as “blue wave.” An empty value lets assistive technology skip it. Do not omit the alt attribute as a shortcut: a missing value may cause an unhelpful filename to be announced. If you work in a content management system, check how it marks images as decorative.
When an image is a link or button, its text alternative should explain the action or destination. A magnifying-glass icon used as a search button needs a label such as “Search,” not “Magnifying glass.” If a linked image sits beside linked text that already names the destination, consider whether both need to be part of the same link so the destination is not announced twice. For a chart or diagram, a short alt text can state its main takeaway, while the surrounding page supplies the figures, labels or steps a reader needs. Alt text alone is rarely a good place for a long data explanation.
Use the page as part of the description
Good alt text works with the caption, heading and body copy. Suppose a page includes a labeled diagram of a community garden. The alt text might say, “Garden plan showing the accessible path connecting the entrance to all four planting beds.” If visitors also need the bed names and locations, put those details in nearby text. That makes the information easier to read, translate and update for everyone, rather than hiding it inside an image description.
Images containing words need extra care. If a poster announces workshop registration details, put those details in page text instead of relying on visitors to read the poster. The poster’s alt text can then briefly identify it, or it can be decorative if it adds nothing beyond the text. For a logo that identifies an organization, the organization’s name is usually more useful than a description of its shapes and colors. Check the immediate context to avoid repeating a name that is already announced.
Make review part of publishing
A small team can use a repeatable workflow. When adding an image, record its purpose, write the alt text in the page’s context, and decide whether any fuller explanation belongs in visible text. Give the reviewer three questions: Would someone understand the image’s contribution without seeing it? Does a linked image name what happens when selected? Is any description merely repeating nearby words?
Review the finished page, not just the image library. An image reused on several pages may need different text each time. If your publishing system applies one stored description everywhere, check each placement before relying on it. You can also read the page with images hidden or use a screen reader to hear how the text fits into the reading order. Treat alt text as part of the content: revisit it when an image, link destination or page message changes.
