SEO best practices for alt text

In a Google Office hours hangout, Google’s John Mueller answered a question about how to use alt text for SEO. Along the way, he dispelled the idea that there was a 16-word limit on alt text and suggested ways to use alt text that would be useful for SEO.

alt text

Alt text is a reference to the alt text for images. The purpose of the image alt text is to describe what is in the image to people who access a web page using a screen reader.

A screen reader is an assistive device that helps people with visual impairments access web documents, among other things.

A screen reader reads computer documents aloud so that the person accessing the documents can hear what is written.

Screenshot of John Mueller from Google

Does Google read more than 16 words as alt text?

John summarized a question that was put to him.

He said it’s from a food blogger:

Google said there are a maximum of 16 words you can use in your alt text.

The question is, does Google read the rest of my alt text and what does this mean for usability? “

Mueller answered the question:

“And I think the important part here is that we don’t have any guidelines as to the duration of your alt.

So from a Google search standpoint, you can put a lot of things in the alt text of an image, if it fits that specific image.”

Alt text limit 16 words?

The person asking the question referred to what they think is Google’s 16-word limit that can be used in alt text.

This idea may have come from a search engine optimization (SEO) test that sought to determine which text in an image was searchable in Google Images.

The test used non-existent words (mainly gibberish) and discovered that Google was unable to find images with more than 16 words to search for.

Using gibberish to test Google results in flawed SEO Test results.

The reason gibberish is a flawed methodology is that Google is designed for actual word order and not designed for gibberish.

So for the chatter it would be very nice of Google to pull the normal algorithm (because it doesn’t apply) and simply try to do a match directly from the query to the webpage, which is not how Google search normally works.

Whether this bug has an impact on SEO testing is an open question.

The point is that Google didn’t enforce the 16 word limit but was generated from SEO test results.

Mueller explains how to use alt text for an image

Mueller then provided an explanation of how Google uses alt text in images and what it means for how alt text is used for SEO purposes.

Mueller continued his answer:

“When it comes to alt text, we mainly use that to better understand the image.

So if someone is searching…in Google Images for something of this type that matches alt text, we can use that to understand that your image is relevant to that alt text on that specific page.

This is kind of a basic use case for alt text.

We also use alt text as part of the page. But that to me, that’s usually something that’s already visible on the page anyway.

So it is not a significant thing for the page itself.

So I’m really going to use it as something that applies to the image and I’m going to use it for ease of use and for Google Images to better understand that specific image.”

What words to use in alternative text

Muller then began explaining how to choose the best words for an image’s alt text.

Mueller continued:

“And I think what might also be worth mentioning is when it comes to Google Images, you don’t necessarily need to describe exactly what’s in the image.

But instead, kind of like what this photo means for your own page.

So if you have a picture of a beach, you can use alt text and say, oh that’s a beach.

But you could also say, this is the beach in front of our hotel or this is the beach we took a picture of when we were doing a chemical cleaning.

These intents are completely different and people will search in different ways on Google Images to find more information there. And always giving that extra context makes sense, in my opinion.”

Use alt text to provide context

John Mueller primarily encouraged SEOs and publishers to use words that provide context to an image within a web page so that the context of how the image fits into the web page’s content becomes clearer when someone with a screen reader comes across the image.

So if you are in doubt about what to put in the alt text for an image, it’s a good idea to think about how the image would describe a person with a visual impairment and then use that description in the alt text.

the quote

Search engine optimization for alt text

Watch at 46:49 Minute Mark:

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