Good alt text explains the useful information an image contributes in the context where it appears. Decorative images should normally have an empty alt attribute so screen readers can skip them. Do not stuff alt text with SEO keywords.
What you’ll need
- The page where the image will appear.
- An understanding of what the image is doing on that page.
- The actual image — not only its filename.
How to do it
Decide whether the image is informative
Ask what somebody would miss if they could not see the image. If the answer is “nothing”, it may be decorative.
Social Piggy illustration — labels are based on the current official help journey and may move when the platform updates its interface.
Write for the context
Describe the information the image adds, not every visible detail. The same image can need different alt text in different contexts.
Handle functional images differently
If an image is inside a link or button, the accessible name should usually describe the action or destination rather than the visual appearance.
Avoid duplication
If a nearby caption or text already gives the same information, repeating it in alt text can create noise for screen-reader users.
Leave decorative images empty
Use an empty alt attribute for genuinely decorative images so assistive technology can ignore them.
For a product, event or guide image, write the alt text for the reason that image is on that page. “image123.webp” and “best marketing SEO UK business” are both poor alternatives.
Common mistakes to avoid
- Starting every alt with “Image of”.
- Keyword stuffing.
- Leaving important informative images with no alternative.
- Writing a description so long that it becomes harder to understand than the image.
Questions people ask
Does alt text help SEO?
Accessible, descriptive image information can help search engines understand context, but accessibility and usefulness should drive the wording.
Should every image have words in alt?
No. Decorative images should generally use empty alt text.
Website Design & Management
Social Piggy can help with the marketing work around this task, without taking away your control of the account.
Research and review
This guide is maintained against current official guidance where available. Platforms can change, so wording and interface labels may move between reviews.