Google on Alt Text SEO and Accessibility
Google on Alt Text SEO and Accessibility
Googlers John Mueller and Lizzi Sassman discuss creating image alt text that works well for those using screen readers, briefly touching on what to do with decorative images and the difficulty of writing alt text that strikes a balance between SEO and accessibility.
Alt Text is for accessibility and SEO?
According to the World Wide Web Consortium (commonly referred to as the W3C), the official body for HTML standards, purpose of image alt text is to make images comprehensible to site visitors who cannot see the content of the images and use screen readers.
Alt text also helps those using screen readers to understand the purpose of the image or become aware of the text contained within the image.
The W3C also says that alt text also has an SEO purpose.
“…if you want your website to be indexed the way it deserves, use the alt attribute to make sure it doesn’t miss important parts of your pages.”
Arguably, the purpose of alt text is to make images understandable and accessible to those who cannot see the image, which includes browser bots.
It takes a surprising amount of thought to get alt text right. The W3C has published an alternative text tutorial for seven different types of image contexts.
Don’t say a picture is a picture
While SEO may require that the screenshot alt text says that the image is a screenshot, for accessibility purposes it is considered redundant (and boring to say that the image is an image).
Lizz Sassman and John Mueller discuss how to solve this problem:
“So one of the best practices is not to start every image with a screenshot, a screenshot, because then it just repeats itself.
We are already aware that it is a picture. You don’t have to say, ‘That’s a picture’ and then the thing.
Just run with any description. And it also doesn’t necessarily have to be a full sentence, I think.
John Mueller: Yes.
Lizzi Sassman: That might just be a descriptive phrase. I don’t think it has to be a complete thought.”
Balancing SEO needs and accessibility
John Mueller introduces the topic of the tension between what is traditional SEO practice regarding image alt text and accessibility requirements.
“John Mueller: Yes, yes. I think that makes a lot of sense.
I mean, the tricky part is probably balancing the two sides. Type of accessibility. What people want from alt text for accessibility.
And then the SEO aspect where you would do some things like… traditionally, you would do some things that might be a little bit different.
Like you would list a bunch of synonyms, for example.
Like, “Oh, this is an ocean beach with waves.”
And it’s the kind of thing where sometimes it makes sense to do it in alt text for SEO reasons, but probably not for accessibility reasons.
And finding that balance is something that is sometimes a bit tricky.
So it’s good to keep an eye on it.”
Something is better than nothing
The important thing about image alt text is that it is bad practice to leave the alt text field empty.
One of the reasons this is a bad practice is that screen readers can start reading image filenames, which is a negative user experience.
Another reason is that it prevents visitors using screen readers from receiving important information that may be in some images.
Then there are the SEO considerations of alt text and proper image indexing and search.
John Mueller recommends adding something to the alt text because something is better than nothing.
“John Mueller: But if you’re just adding alt text for the first time, sometimes even any alt text is better than nothing.
Lizzi Sassman: Like nothing.
At least starting with something, but then, what can you do to even improve on top of that.”
Alternative text and decorative images
Lizzi Sassman then discussed what to do with decorative paintings.
The first problem is distinguishing whether the image is truly decorative or conceptual and contributes to the meaning of the content, in which case the challenge is how to convey the conceptual image.
“And that’s definitely something that… I think I struggle with more, like the more you get into decorative imagery, or things that aren’t…
I don’t know… the search results thing is pretty simple.
But once you get into things like, “Oh, this is a concept,” or “It’s decorative,” so no…
There are some places that say, ‘Oh, you don’t have to put alt text in a decorative image.’
For example, if it’s there just for aesthetics, then it’s better to leave the alt text blank.
But on the other hand, why would I put it there? There was a reason to put it there.
So shouldn’t we have something that fills that void for the experience of someone who can’t see the picture?
Shouldn’t we have a replacement thing? It served a purpose.
We put it there for a reason, as it would be an alternate experience if that information was still transmitted, I guess?
So for Googlebot, as for work.
Sometimes we have these, I guess, what would be categorized as a decorative painting.
Where it’s like a Googlebot exploring the web, or something.
Or is it conveying some kind of idea, and should the alt text focus on the idea? Or like, ‘Oh, it’s Googlebot with friends.’
Or it’s Googlebot… like spamming your computer, and then, being happy at the end.
It’s like you describe what’s going on there, so you still kind of get an idea of what was supposed to be there, I guess, one of the things that… yeah, it confuses me.
John Mueller: Yes. I mean from a personal point of view, I would definitely add alt text to images like this, because they are kind of unique and special.
It’s not… I don’t know… a floral background, or something.
It’s actually something that people have spent a lot of time creating that image.
And it’s also something that people might want to find in search results.
So if you’re looking for a Googlebot, because we spend so much time creating all these images, it would be nice to be able to find them as well.”
The W3C has published a full page of documentation on how to handle alt text for decorative images.
This is official W3C recommendation:
“Decorative images do not add information to the content of the page.
For example, the information provided by an image may already be provided by adjacent text, or an image may be included to make a web page more visually appealing.
In these cases, null (empty) alt text should be specified (alt=””) so that assistive technologies, such as screen readers, can ignore them.
Text values for these types of images would add audible clutter to the screen reader output or could distract the user if the subject is different from that of the adjacent text.”
The W3C also suggests four ways to identify decorative images.
Four tests to see if a picture is decorative:
- The image is used to style the document (look and feel)
- If it is an image that complements the text of the link
- It does not contribute information to the textual content
- The image is described by the surrounding textual content
Ultimately, it’s up to the author to decide what’s best for the image’s alt text.
As Google said, something is better than nothing. So if the image doesn’t provide information, just use a null value for the alt text, which is encoded with alt=””
Listen to this part of the Google Podcast at 15:17 minutes:
Featured Image Shutterstock/Roman Samborskyi
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