Adding Alt Text to Images
What is alternative text?
Images help bring webpages and documents to life. They can make complex ideas clearer and help all users — including those with cognitive disabilities — better understand your content.
Alternative text, or alt text, ensures those same images are accessible to people who are blind, have low vision, or use assistive technology.
When a screen reader encounters an image, it reads the alt text aloud, describing the image so users can understand its purpose and context.
How do we write alt text?
Effective alt text briefly describes the essential information in an image — usually in fewer than 100 characters. Ask yourself: What message does this image convey? Then write that message clearly and concisely. For example:
Do: Multiple students sit on the steps of the campus center, in front of the mural, during a sunny day.
Don't: Students
Although it should not be used exclusively to provide information about the image, the caption field can be used to supplement the information already in the alt text.
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Students sitting on the steps of the Campus Center.
It is not necessary to start your alt text with "image of" or "picture of" since screen readers already announce images, and the text should end with a period to create a more natural pause and easier listening experience. If there is text visible in the image, (eg. a sign, hat, t-shirt, etc.) that should be included in your alt text. If the image conveys complex information (such as a detailed chart or infographic), provide that information in another accessible format. Do not rely solely on PDFs, as they very often are not accessible.
Learn how to add alt text to your website images.
Alt text quick tips
- Focus on meaning, not just appearance.
- Keep it short (under 100 characters).
- Mark purely decorative images as decorative instead of writing alt text.
- Include visible text from the image.
What other benefits does alt text provide?
Alt text helps more than just screen reader users; if an image fails to load on a slow or unstable internet connection, the alt text will appear in its place. Additionally, search engines like Google use alt text to understand what’s on your page, which can improve SEO and make your content easier to find.