Alt Text Explained: 6 Checks for Useful Image Descriptions
What should image alt text say? Start with the job the image is doing. This short video explains six points, with written steps and practical notes below.
1:47 · No narration: the video shows each step as text on screen, and every step is written out below, with buttons that jump the video to it.
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The six points in the video
The video is silent. These are its on-screen headings, explanations and labels, followed by supporting notes.
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Step 1: Ask why the image is here
Its purpose decides the useful text alternative.
On-screen labels: Information; Decoration; An action.
The same image can serve different purposes on different pages. Work out what the reader needs from it in this context.
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Step 2: Describe useful information
Keep the wording relevant to the page.
On-screen labels: What matters; Page context; Concise wording.
Describe the information that matters to the page. Avoid adding unrelated keywords or repeating surrounding text without a reason.
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Step 3: Handle decoration correctly
Purely decorative images usually need empty alt text.
On-screen labels: No extra information; Empty alternative; Avoid repeated noise.
An empty alt attribute is usually appropriate for a purely decorative image. Omitting the attribute entirely can produce a different experience.
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Step 4: Explain linked images
Describe the action or destination the image provides.
On-screen labels: Useful link purpose; Clear action; Expected destination.
When an image provides a link or action, its accessible name should communicate the destination or function.
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Step 5: Support complex diagrams
Give detailed information in nearby text too.
On-screen labels: Short alternative; Full explanation; Accessible details.
A short alt description cannot carry all the detail in a complex chart or diagram. Supply the full useful information in nearby accessible text.
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Step 6: Review it in context
Check the information still makes sense without sight.
On-screen labels: Page meaning; Image purpose; Useful equivalent.
Check whether the page’s meaning and actions remain understandable when the image itself is not available to the reader.
A practical check for your business
Review images in the actual page context. Decide whether each adds information, serves as decoration or provides a link or control. Put detailed explanations of complex diagrams in accessible page text as well as supplying a short alternative.
Sources and further detail
Common questions
Should decorative images have detailed alt text?
Pure decoration usually needs an empty alt attribute. The decision depends on the image’s purpose in the page.
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