Write useful image descriptions
Identify an image’s purpose, describe the information it adds and avoid repeating captions or surrounding text without a reason.
Follow the method ↓
The answer in 30 seconds
The same photograph may provide evidence in one page and atmosphere in another. Imagine removing it: what would the reader lose? That question helps you decide what a useful description needs to convey.
Alternative text depends on the image’s role in its page. Describe the information it contributes; when an image is a link or control, describe the action or destination.
Examples to adapt
The useful information is the action and file, not the arrow’s colour.
A long description may interrupt reading without adding useful information.
Follow the method
- 1Identify the role
Separate decorative, informative and functional images. A decorative web image may need an empty alternative.
- 2Write the useful detail
Describe what matters in context without adding keyword lists. Avoid assumptions about someone’s identity or intentions.
- 3Handle complex material
For a chart, provide brief orientation and make the values or conclusion available in nearby text or a table.
- 4Read the complete page
Read the heading, paragraph, alternative and caption together. Remove repetition and check that links still make sense without their images.
A checklist to keep
Use these checks to record your observations. They are a reading aid, not an automatic assessment.
| Check | What to examine | Action |
|---|---|---|
| Decorative | No additional information | Empty alternative |
| Informative | Relevant detail | Concise description |
| Functional | Action or destination | Useful label |
| Complex | Data and interpretation | Associated text or table |
Free, no sign-up. UTF-8 text with semicolon-separated columns.
What to check
Context determines the description.
Visible captions and alternatives may have different purposes.
Do not describe details you cannot establish.
Common questions
Should I start with image of?
Usually you can go straight to the useful information.
Can an alternative contain an entire chart?
Put lengthy explanations in accessible nearby content.
Sources and documentation
Documentation consulted on . Examples are illustrative; interfaces and results may change.