SEO for Images: What Is Image Alt Text And How To Do Image Optimization

Image alt text is used when defining images in HTML code. Alt text is not a tag. It’s an attribute that is used in a <img> tag.

It’s also known as an alternative text or a sub-description.

Oleg Cassini Image Alt Text on Blog Page
Oleg Cassini Image Alt Text on Blog Page

What is the Importance of Image Alt Texts in SEO?

  1. When an image alt text matches a users’ search, the image is shown in the search results.
  2. Google algorithms are still in the learning process to better understand what the content is about and which user is addressing it. Writing alt text to define visual content will hereby be an important step when you want to be listed in the relevant image search results.
  3. Although there are three types of learning styles: auditory, visual, and kinesthetic, most people have at least two of these learning styles. According to the research of the National Biotechnology Information Center, 65% of people learn more easily with visual perception. With content-compliant and descriptive visual or infographic sharing, visitors can remember and share your content easily. This also means that your content would be more helpful in transferring information. So, by using visuals related to the content and a correctly written sub-text, you can reach a more relevant user audience.
  4. In 2019, the number of mobile users is expected to be 4.68 billion. This means that more than 65% of the world's population are mobile users. As a mobile user, you know that during the day visual and video calls are occurring more often than ordinary text searches. With image alt text, you can take it a step further and deliver your message to more than 65% of the world's population.
  5. For some technical reasons (internet connection speed, server problems, incorrect coding, etc.), images may not be displayed on the page. In such cases, the subtext content provides the user with a text describing the image.
  6. In 2050, the number of people with visual disabilities is expected to be 115 million. When a sub-text is left blank, disabled users cannot know what the image content on the page is about; however, sub-text can tell what the image is displaying.

On-Page Image Alt Text Optimization

  • Start with image optimization. Image alt texts won’t make sense unless you do visual compression first.
  • Focus on user behavior. Why did the user come to visit my content or page? What do they want to read or see? Bring together some common answers to these questions, summarize the subject, and create the image alt text.
  • You can add your most important keywords in the alt text - but be careful not to do keyword stuffing in an alt text or in textual content. The use of keywords only for search engines, such as in the example below, do not help the user.
alt="Mailbox Red Mailbox that is Between Two Windows"
The Red Mailbox which was Used In The Netherlands is Between Two Windows
The Red Mailbox which was Used In The Netherlands is Between Two Windows
  • Above I have mentioned the importance of image alt text. Think about all of these items and describe your image in a relevant way.
  • The following image alt text example is quite insufficient for defining the visual on the right.
<img src="" alt="Old Mailbox">
  • Remember that there are users who are not able to see the image, and Google bots are still in the learning stage. That is why it would be a more accurate approach to define it as in the following example.
<img src="" alt="The Red Mailbox which was Used In The Netherlands is Between Two Windows">
  • Don’t use keywords like image, photo etc. in the image alt text itself, as such explanation may be quite unnecessary. The alt text already defines the image or the photo, and this repetition will not be useful in terms of user experience or SEO.
alt="The Image of a Red Mailbox Between Two Windows Which Was Used in the Netherlands"
  • You can add the brand name to the image alt text. In this way you will be targeting both user and brand queries in the SERPs.
  • Also, the same logic applies when it comes to CTA buttons in the image alt text. When writing alt text for contact buttons or social media buttons, do not use the word “button” itself. “Contact” or “Instagram” is enough to describe the button.

An Example of Our Experience About Image Alt Text Optimization in SEO

Since the beginning of mid-December 2018, we have seen an increase in clicks and impressions on our client’s Google Search Console account, for which we specifically do image SEO. We’ve started adding image alt texts to the images used in all product and blog pages before December 2018.

Google Search Console Image Search Performance Last 6 Months
Google Search Console Image Search Performance Last 6 Months

When it comes to noticing the effects of SEO, you know that this is a long term process. You should also know that customers who approach the topic with long-term perspectives have always been one step ahead in SEO.

After our optimizations, we found that the CTR of image searches was better on desktop devices than mobile. The fact was that 85% of our customers' targeted audience was using mobile; so actually mobile should have been involved in the search process as much as desktop.

Later on, we realized that the image alt texts on the mobile site were not added to the images. We told our customers about the importance of the mobile situation and requested the implementation of our suggestions.

SEO Project Image Search Results on Google Search Console Reports
SEO Project Image Search Results on Google Search Console Reports

After these implementations, the image mobile clicks have started to increase faster than desktop when we made a 3-month period comparison in GSC of the same customer (see the difference). And that was a significant improvement for a customer with 85% mobile users.

What are the Points to Consider in Image SEO?

Image SEO for User Intent & Experience

  1. Use images that match with pages’ content.
  2. Use original images as much as possible. I know that we love stock images; they are easy to find, life-savers, etc. but none of them is as original as your own shot.
  3. Try to position the images around the content as much as possible. For example, if you're talking about 5 ways to be happy in the middle of a page, use the image in the center of the page; not at the end. In addition to negatively impacting the user experience, this behavior may also give a wrong signal to the Google bots.
  4. Write the image title, filename, and define it by image alt text. Google says that “my-new-black-kitten.jpg is better than IMG00023.JPG”
  5. Don’t write important messages on images itself. Visually impaired users will not be able to see the text on the image, and also the language of the text on an image will not change when users translate the page content with Google Translate. Make sure that the text on the image is selectable.
  6. Mobile-First-Indexing! Google's crawling, indexing and ranking operations are based entirely on the mobile version of the page which we call mobile priority index. In cases where the image size is too large, the mobile user (aka users who want to get results on mobile immediately) can leave the page without waiting for the page to fully load. The data that each negative user experience gives to Google is a very important factor for Google to evaluate your page; so it would not make sense to use high-dimensional images. For the relationship and optimizations between image and page load speed, you can read the following sources:
  7. Image SEO by Image Quality and Format

  8. The image that has a good quality is better for the user experience. Nobody wants to share a pixel-by-pixel image or spend time to understand it.
  9. Screen sizes are different for mobile, tablet, and desktop. The images with a poor resolution are distorted at different screen sizes and do not give a good experience for users.
  10. Use the <img srcset> or <picture> code to adapt the size or format of the image to the responsive web.
  11. Other Important Image SEO Points

  12. Google Images supports structured data for the “Products, Video and Recipe” pages. By adding the relevant structured data to the page HTML, you can increase the likelihood of being included in the relevant image search results.
  13. Create a sitemap XML file for images only.
  14. Images must be accessible to Google bots and communicable to users. So make sure that the images of the website are not blocked by the robot.txt file.
User-agent: Googlebot 
User-agent: Googlebot-image 

Frequently Asked Questions About Image SEO and Image Alt Text

Does Google Really Consider Image Alt Text?

Yes. One of the most important factors that Google considers is the image alt text when visuals are blocked from being displayed by the browser due to technical problems.

Should Image Alt Text Be Added to All Images?

Focusing on accessibility and user experience, which we have to do when we consider organic traffic, then yes; image alt text should be added to all images.

Is There Any Character Limit for the Image Alt Text?

While some sources give a character limit between 100 and 120, Google has not made a statement that there is a character limit. Just make sure to define images with a relevant topic.

Should the Brand Name Be at the End or at the Beginning of the Image Subtitle?

If your brand-image search results are already pointing to your website; you can use the brand name at the end of the image alt text. By following this way, you can use the search term you've targeted first. But there is no explanation by Google about this issue.

Do I Need to Translate Image Alt texts on Sites with Multiple Language Options?

If the page has a different language option, you should also convert image alt text to that language. For example, the image alt texts have to be in Turkish when the page where the image is located on is in Turkish as well.

Is There A Need for Image Optimization with Machine Learning?

Thanks to machine learning technology, Google is increasingly mastering the detection and reading of images, but it is still in its infancy. So you need to keep the site and page content clear with image alt texts. However, this situation will of course change in the future. But there are still different image SEO techniques that people have to do themselves.

Google Machine Learning Building
Google Machine Learning Building

The Importance of Images in SEO in the Last 12 Years: What Has Been Discussed from 2007 to 2019?

Gary Illyes Answered the Most Curious Questions about Image SEO at the Reddit AMA Session, 2019

February 2019

Gary answered a lot of questions from the Reddit AMA session. You can find all the questions and answers in the link at the end of the topic. The questions about the visuals were as follows:

Question: “A simple question I'm very curious about Images as a part of Web Search. Is Google's image recognition technology used as a relevancy signal within the document selection algorithm within the index? If that's not the case, would you forsee it in the next future?”

Garry: "Yea."

Question: "Is there anything that most SEO's tend to overlook/not pay attention to?"

Garry: "Google Images and Video search is often overlooked, but they have massive potential."

Question: "Will web accessibility be considered direct ranking factor for images and video rankings?"

Garry: "Unfortunately, no."

You can visit Reddit for all the questions and answers from Gary Illyes' Reddit AMA session.

Google Image Searches Tips, 2018

October 2018

Gary Illyes spoke about the most current tips on how to be listed in Google search results at his October 2018 conference:

  • Check and make sure that your images are not blocked by the robot.txt file.
  • An image sitemap is a must as it allows the indexing of images a lot faster than normal browsing.
  • There is no character limit for alt text, but a complete and accurate definition is crucial.
  • Adding structured data to images and website pages increase the likelihood of being listed in image search results.…

The Importance of Using Image Custom Sitemap, 2010+

Since 2010

Actually, the rule is very simple. Google has been publishing many guidelines from the past to the present to ensure that user search results and Google search results are relevant. These guidelines are often updated with new developments, but always serve the same purpose: User experience, user behavior...

Google Webmaster Blog Highlights Web Speed, 2010

April 2010

Content that underlines the importance of visuals in terms of SEO as well as all other issues concerning web speed; SEO emphasized that web speed can be improved with image optimization. Tightening the size of the photos was one of the most important issues that would affect both the user experience and web speed.

Image Alt Labeling Techniques That Still Appear Today, Announced, 2007

December 2007

Matt Cutts shared the video themed Google visual publishing guidelines, emphasizing the importance of image alt texts. Even today, the directive titles that are still important are as follows; filename, sub-attribute, content, and captions.

Post date: 26 Mar 2019

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