The same image can need different descriptions in different places. A photo used to identify a product does a different job from the same photo used as a visual background. Before writing alternative text, decide what information or action the image contributes to this particular page.
The role distinctions below follow the World Wide Web Consortium's Web Accessibility Initiative image guidance. The examples and review worksheet are original. This is a practical starting point for image text alternatives, not a complete accessibility audit.
Ask what would be missing without the image
Look at the image together with its heading, caption, nearby text, and any link or button containing it. If the image carries information, the text alternative should communicate the relevant meaning. It does not need to inventory every visible object.
For a fictional craft tutorial, a close-up photograph might show a folded paper corner aligned with a marked edge. A useful description could explain that alignment. The color of the table and the photographer's shadow probably do not help the reader understand the step.
Write the purpose in a private note first: “This image shows where the fold should meet the guide.” Then draft the alternative text around that purpose. If you cannot explain why the image is on the page, resolve that editorial question before polishing the description.
Distinguish information from decoration
Some images add atmosphere or repeat information that is already available as nearby text. W3C's guidance treats purely decorative images differently from informative ones. For an ordinary HTML image that is decorative, an empty alt attribute can keep it from adding an unnecessary description.
Empty alternative text is a deliberate implementation choice, not the same instruction as forgetting to provide it. Use your publishing system's supported decorative-image option or confirm the output with the person responsible for the page.
Do not classify an image as decorative merely because describing it takes effort. A diagram that explains an assembly step carries information even if the surrounding article is long. Conversely, a repeated flourish beside every heading may not need its own spoken description.
Describe the action when the image is a control
If an image is the only meaningful content of a link or button, its text alternative should explain the destination or action. Describing its appearance alone can leave the control's purpose unclear.
For example, in a fictional image gallery, a small arrow might open the next photograph. The useful label would communicate that action, such as “Next photograph,” rather than only “right-pointing arrow.” If a visible text label already provides the accessible name, the implementation needs to avoid unnecessary repetition.
Check the whole control, not just the image-file metadata. A description saved in an asset library may not be the text actually exposed by the published link or button. The person implementing the page should verify how the final control is named.
Keep the description faithful to the image
Read your draft while looking at the actual file. Remove details you inferred but cannot support. Do not identify a person, material, location, or product feature solely because the image resembles something familiar.
For a product photograph, concentrate on relevant visible details, such as an open compartment or the arrangement of included parts, while keeping factual product specifications tied to verified product information. Do not turn a description into a sales pitch or add a keyword list.
If an image contains important wording that is not available elsewhere, make that information available in text. Check the wording manually. A guessed letter or number can change the meaning of a label, sign, or instruction.
Give complex images room for an explanation
A chart, map, or detailed diagram may contain more information than a brief alternative can usefully carry. W3C's decision guidance recommends making complex information available elsewhere on the page. Plan a clear nearby explanation or an appropriate detailed alternative instead of squeezing every detail into one short field.
For a fictional comparison chart, the page might need the categories, values, units, and the relationship the chart is meant to show. A label such as “comparison chart” identifies the object but does not communicate those results. Work from the underlying verified information when preparing the text.
Review each image in its final context
Keep a short worksheet with the image filename, page location, purpose, draft alternative text, and reviewer. Add a note when the image is intentionally decorative or needs a longer explanation.
Read the surrounding content with the proposed text in sequence. Does it add the information the image contributes? Does it repeat the caption unnecessarily? Does a linked image explain where it goes? After publishing, check that the intended text or decorative treatment survived the publishing workflow.
Revisit the description when the image, crop, or page purpose changes. An accurate description of an earlier version can become wrong after an edit. The goal is a useful alternative for this image in this place, with enough context to understand what the reader would otherwise miss.
