Last modified 11/6/2023

Images require alternative text for individuals who have visual impairments, including those who have color-blindness. Alt text is a brief textual description that serves as a substitute for images and conveys their content and purpose to individuals who may not be able to see them. By writing effective alt text, you can ensure that your website is accessible to people with visual impairments and create a more inclusive online experience.

Learn how to write alt text for images

Add or update alt text for images in Microsoft Products

Adding alt text in images in PDFs with Adobe Acrobat

Insert/Edit Images in Omni CMS

Add Alt Text to Images in InDesign

Why is writing alt text important?

Here are some key reasons:

  1. Accessibility for Screen Reader Users: Screen readers, which are assistive technologies used by individuals with visual impairments, rely on alt text to describe images on web pages. By providing descriptive and accurate alt text, you enable screen reader users to understand the visual elements within your content, making it more accessible and inclusive.

  2. Context and Understanding: Alt text serves as a crucial means of conveying important information and context that may be visually apparent in an image. It allows individuals who cannot see the image to comprehend its purpose, content, and any relevant details. Well-written alt text ensures that no one misses out on the information or message your images convey.

  3. Search Engine Optimization (SEO): Alt text plays a vital role in improving your website's search engine visibility and discoverability. Search engines rely on alt text to understand the content of images and include them in search results. By providing accurate and relevant alt text, you enhance your website's SEO, potentially attracting more visitors and increasing your online presence.

  4. User Experience and Engagement: Alt text contributes to a better overall user experience. When users encounter broken images or encounter images that do not load properly, alt text provides context and prevents confusion. Additionally, alt text allows users to navigate and explore your website more effectively, as they can understand the purpose of images even if they choose not to view them.

In My Own Words

Meet V, who relies on alternative text for images.

Types of Images

Information Images

Information images are images not used as a like. They are present to convey meaning or information. The alternative text foir information images should describe the image and its purpose for supporting the page content.

Action Images (links, etc)

Action images are images that have an action, such as a linked image. The alternative text for an action image should provide context for the target of the link.

Larger data

Larger data images, my not be images but other forms of non-text content such as charts and graphs. The information present in the graph or chart needs to have a text equivalent.If information is too large for an alt tag, included the data table for the chart or graph.


Avoid if possible. Text embedded into image files are not accessible to some assistive technologies. Instead it is best to use HTML for text. If you must use an image of text, then use the text in the image as the alt tag, do not identify the specific image scene or elements. The text is typically the important information in a text image.

Decorative images

Decorative images do not have a significant function except for decoration. These images can have a blank or null alt text (alt=""). Please note, the OU campus editor requires all images to have an image description before they can be uploaded. In these cases, it is best to add the image description anyway.

Blinking Content

Avoid blinking content. Flashing or blinking content (particularly content in red) can cause seizures in people with photosensitive epilepsy as well as other photosensitive seizure disorders. Limit use to only when necessary. If blinking conent is necessary content should not flash more than three times in one second.

More Resources for Accessible Images