Decorative or Informative? How to Decide When an Image Needs Alt Text
Short answer. An image needs meaningful alt text when it communicates information, performs a function or contributes to understanding the surrounding content. A decorative image can usually have empty alt text so screen readers skip it. The decision depends on what the image does in context, not simply what it looks like.
- Decide an image's purpose before writing its description.
- Use empty alt text for genuinely decorative images.
- Describe meaningful information without repeating nearby text.
- Treat functional images according to the action they perform.
- Review images in their page context, not in isolation.
Start with the image's job
The first question is not what an image depicts. It is what the image contributes to the page. A photograph might illustrate a topic, provide evidence, identify a person or communicate information that the surrounding text never explains. A small decorative flourish might have no informational purpose at all. These images can look equally prominent on screen while requiring completely different treatment in alternative text.
A useful decision starts with three possibilities: the image is decorative, informative or functional. Some images combine these roles. A photograph in a news article may illustrate an event, while a diagram in the same article explains a process. An image used as a link may also have a functional purpose that takes priority when its description is written.
- Decorative: adds visual styling without meaningful information.
- Informative: communicates facts, context, evidence or an idea.
- Functional: performs an action, such as opening a page or submitting a form.
Use a decision tree before writing
Ask whether removing the image would cause someone using a screen reader to miss information or functionality. If the answer is no, and the image adds no meaningful context, it is probably decorative. In that situation, the HTML alt attribute should generally be empty: alt="". This allows assistive technology to skip the image without announcing a filename or unnecessary description.
If removing the image would remove information, it needs a description. Identify the main information first, then decide how much detail is necessary. If the image is interactive, describe its purpose or destination. A magnifying glass button, for example, should communicate that it opens image zoom, not simply that it contains a magnifying glass.
A practical decision tree is simple: Does the image communicate information? If not, is it purely decorative? If yes, use empty alt text. If it communicates information, describe the relevant information. If it performs an action, describe the action. If its meaning depends on surrounding text, use that context when writing the description.
- Remove the image mentally and consider what information disappears.
- Check whether the image is a link, button or control.
- Look for nearby text that already communicates the same information.
- Choose empty or meaningful alt text according to the image's purpose.
Write descriptions that carry useful information
Good alt text is selective. It identifies the information a reader needs without turning every visible detail into a sentence. For example, a photograph accompanying a report about a flooded street might need the description "Cars travel through floodwater on a city street." The description communicates the scene and its relevant context. It does not need to list every vehicle, building or visible reflection.
How to write alt text also depends on the content type. A chart may need its main trend or comparison described, while a diagram may need its relationships explained. If the information is complex, a short alt description can introduce the image and direct readers to a longer explanation in the surrounding page text. The longer explanation should be available to everyone, not hidden exclusively from sighted readers.
Avoid automatic openings such as "Image of" or "Picture of" when they add no useful information. Screen readers generally identify image elements themselves, although the exact announcement depends on the software and settings. Start with the subject or information that matters.
Describe people in photographs with care
Alt text for people in photos should prioritize visible, relevant information and avoid unsupported conclusions. A description can mention clothing, position, activity and the surrounding setting. For example, "A person in a blue jacket stands beside a bicycle outside a station" communicates observable details without guessing the person's occupation, identity or reason for being there.
Names, relationships, age, ethnicity, gender identity and emotional states require particular care. Include identifying information when it is reliably established and relevant to the content. A caption or accompanying article may provide context, but a photograph alone rarely establishes someone's name or personal circumstances. A visible smile also does not prove that a person feels happy.
The purpose of describing a person is not to produce a complete inventory of appearance. Select details that help readers understand the image's role in the story. If the person's identity is irrelevant, there is no need to invent or infer one.
Avoid repetition and unnecessary detail
An image's description should work with the text around it. If a product heading already says "Red cotton backpack," repeating those exact words in the image description may waste the reader's time. A useful description might instead identify a feature the heading omits, such as the side pocket or adjustable straps. If several product images show different views, each should communicate its distinct contribution.
A common editorial mistake is treating every image as an opportunity to describe everything visible. A decorative divider does not need an elaborate description. A small icon beside the word "Search" may need no additional wording if the button already has an accessible name. The objective is to preserve information and function, not maximize the number of words.
Check the description in its publishing context
An image can change roles when it moves to another part of a page. A decorative photograph in a visual banner may become informative when used as the only illustration of an event. Similarly, an icon that is decorative beside a fully labeled button may become essential when used alone as a control. Review the actual implementation, including links, captions and surrounding headings.
For a final editorial check, compare the experience of someone who can see the image with someone who receives its alternative text. Are the important facts available to both? Does the description repeat an adjacent caption? Does a screen reader encounter meaningless filenames or duplicate announcements? These questions help identify problems that a spelling check cannot catch. Start with the most prominent images on one page and document whether each is decorative, informative or functional.
Questions readers ask
Should every image have an alt attribute?
For ordinary HTML images, an alt attribute should be provided. Its value can be empty when the image is decorative, or contain a meaningful description when the image contributes information or function.
What is an example of good alt text for a photograph?
For a photograph of a cyclist waiting at a crossing, "A cyclist waits beside a pedestrian crossing in the rain" gives a concise account of the relevant scene. The best wording still depends on why the photograph appears.
Can a caption replace alt text?
A visible caption and alternative text can serve different purposes. If the caption already provides the relevant information, the image description may be shorter or empty when the image adds nothing else.
How should a complex infographic be described?
Provide concise alt text identifying the infographic and make a complete text equivalent available nearby. That equivalent should communicate labels, values, relationships and conclusions that matter.