There's No Alternative to Good ALT Text

What is ALT text?

ALT text (ALT being short for alternative) is referred to in several different ways: ALT text, ALT tag, ALT attribute, ALT description and simply, alternative text.

ALT text serves several purposes:

  1. It is read by screen readers.



  2. It appears on a webpage if the image fails to load.
    Broken image icon with the words Dog Walking

  3. It reveals content to Google...it impacts SEO
    According to Google, "Google uses alt text along with computer vision algorithms and the contents of the page to understand the subject matter of the image." Google Images best practices. When search engines crawl a page, images with properly constructed ALT text impact how the page gets indexed and where it ranks.

  4. It helps you rank in Google Images
    1. "Google Images is the world’s second-largest search engine. It’s responsible for 20.45% of all online searches, putting it ahead of YouTube, Bing, and other search engines combined. This means there’s an opportunity to drive traffic from Google Images." Alt Text for SEO: How to Optimize Your Images ~ Joshua Hardwick
    2. "One of the most important things image alt text can do for you is turn your images into hyperlinked search results -- giving your website yet another way to receive organic visitors." Image Alt Text: What It Is, How to Write It, and Why It Matters to SEO ~ Braden Becker

Some Best Practices to Remember

Same image, different context:  If you have an image – say it is the feature image on your homepage, but it’s a thumbnail on your sitemap – you will need to develop different ALT text for each image. A simple solution for this specific scenario can be to use the same ALT text for both images but simply add the word “Thumbnail” to the ALT text for the thumbnail image.

Photos of people and their identity: This can be complicated. If possible, ask people how they would like to be referred to in the ALT text. (This goes for any caption that may be assigned to that photo as well.) Don’t guess at someone’s gender.

If you decide to use gender, for example, "female professor," make sure you use it consistently ("male professor").

Emily Lewis, author of Best Practices for Image Text Alternatives, says, "... this advice applies to any type of "identity” information, whether that is gender, racial, cultural or other ways people identify themselves."

Length of good ALT text: There is no character limit for ALT text. With that said, please keep in mind that not all screen readers have the capability to "Pause" ALT text as it is being read. So if you need to write a lengthy ALT text to describe an image properly, you may want to consider including that text directly on the page.

Clickable images: There is usually no need for "traditional" ALT text for clickable images. There is, however, a need to indicate the purpose and destination of the linked image.

Images with captions: Normally, image captions only give basic information and do not adequately describe an image. Therefore, you usually need ALT text for images that have captions.

Referring to the image by using the word "image": When writing ALT text, do not use the phrases “image of,” “photo of,” “picture of” or anything similar. Since Alt text is referring to an image, there is no need to repeat that. Also, many screen readers announce to users that what they are hearing is a description of an image.

So, what does good ALT text read like?

Examples of bad, good and better ALT text from Moz using three different examples, each more complex.

Resources

Image courtesy of Callia Web

Examples courtesy of Moz

Maggie Vaughan, CPACC
~ friend of DubBot, A11Y practitioner in higher ed