Alternate text is provided to a website visitor when an image is not visually perceivable. There are numerous reasons a visitor may not see an image. They may be using an assistive technology to read the website, called a screen reader, or they may have turned images off in order to browse faster or sometimes there are just glitches.
Google and other search engines rank pages higher in search results that have alternate text. Contextually relevant alternate text that uses keywords will improve search result relevance.
How to Write Alternate Text
Your alternate text should perform the same function as the image. First, think of it as an equivalent, then think if is anything that could be in the description that would add value. The rules, best practices and tips below should help.
Rules & Best Practices
- Because the browser could perceive them as code and break the site, do not use these characters in your alternate text: # % & ‘ ^ ` ~ + ; = ) ( \ / : * “ < > | [ ] Don’t use quotation marks.
- Be careful not to mislabel people. Only describe race or gender if it’s relevant and you know the identity of the people in the image. In most cases it’s fine to say “person” or “people” rather than risk misgendering them.
- If the image has text in it, your alternate text should have the same text. Remember, if the image is not visible then the text on the image is not visible.
- If the image is a link:
- the alternate text should describe the function of the link, not necessarily the image itself. For example, a back arrow should say “Return to previous page” not “Arrow”. The best alt text for a linked image is frequently the title of the linked page or description of the content.
- do not include “link to” since screen readers will announce that the image is a “link graphic” before reading the alt text.
- see more about the importance of text for links.
- Images in PDF and Word documents should also contain alternate text. You should be able to add alternate text to your documents using the context menu.
- The file name, image byte size, created date, or other data are not usually appropriate alt text.
- Avoid using the word “image” to describe your image. Screen readers will announce that the image is a graphic before reading the alt text.
- “Logo” is also not helpful. Use the words/letters in the graphic or other messaging related to the brand.
- Try not to be redundant with other text on the page. An image next to a Title should not have the same alternate text as the text in the Title. If this is proving to be a challenge, read the tips below and the article linked under the Image Descriptions section. However, redundancy is not the worst issue and repetition of important messages is sometimes desirable or may be unavoidable.
- There is no requirement for the length or number of characters. However, some sources arbitrarily recommend around 100 characters. Most likely this is to encourage staying concise. We recommend trying to be concise but also accurate.
- Never use acronyms or abbreviations. Write the words so that screen readers will read them correctly.
Tips & Suggestions
- You should develop a site-wide strategy that defines your editorial character for copywriting of your alternate text.
- Break down the image:
- describe the noun, object, focus, or subject
- the action or what’s happening and
- the context or environment.
- Sometimes it helps to imagine describing the image to someone over the phone.
- Ask yourself, “if I could not use the image here, what would I write instead?”
- Many images are chosen for emotional value. Your alternate text should be written to provide the same emotional impact.
- Consider the keywords for the message your image is supporting. If appropriate, using them in the alt text can help improve search engine rankings.
- Don’t be afraid to be creative. We are the College of Fine Arts, after all.
- Trouble describing works of visual art? Take some tips from the Art in America article “How Museums are Making Artworks Accessible to Blind People Online“
- Explore the resources on the Alt-Text as Poetry website.
Writing alternate text is only one aspect of great content. The article How to Write Image Descriptions from the UX Collective provides an easy-to-follow strategy and also makes the compelling argument that: “By writing image descriptions, we show support of cross-disability solidarity and cross-movement solidarity.” It includes a very helpful section on describing race and gender.
The Web team and public relations staff are happy to discuss further if you have any questions.
Complex images can be very challenging. A good place to start is on the WebAIM Accessible Images page. See the section on Flowcharts, Graphs, and Complex Data and Visuals on the Additional ADA Issues page.