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Image ALT Text In SEO (Complete Guide)

This guide explains image ALT text.

Below, you’ll get a complete overview of image ALT text, including what it is, how it works, the importance of image ALT attributes, and ways to optimize it for search engine optimization (SEO).

The ultimate goal here is to help you understand every aspect of image ALT text and how it applies to websites and the field of SEO in digital marketing.

Image ALT Text

What Is Image ALT Text?

Image ALT text is alternative text for images that describes the content of the image as it relates to the web page or document. Image ALT text attributes are used by screen reader software and crawled by search engine spiders to index images in the search engine results pages (SERPs).

Purpose of Image ALT Text In SEO

The primary purpose of image ALT text in SEO is to improve on-page search engine optimization by giving Google’s ranking algorithm extra keyword data it can use to verify the main topics for the page. A secondary purpose is to give search engine crawlers important data to properly index and rank images in the SERPs for relevant queries.

Additionally, ALT text is used to enhance the user experience (another part of the ranking algorithms) by giving descriptive information for images to make websites more accessible to users with visual impairments. ALT attributes are also displayed as text in place of photos or graphics that fail to load on the page so the visitor understands the intended purpose of the image.

Importance of Image ALT Text

Image ALT text is important for SEO because image ALT text attributes are a contributing factor to search engine rankings. Well-written ALT tags also enhance your website’s accessibility, improve the user experience, and provide additional data that enables web crawlers to increase the contextual accuracy of image search results.

A summary of the top benefits of using image ALT text include:

  • Improving On-Page SEO signals.
  • Helping images rank correctly in Google Image Search.
  • Enhancing the user experience when images fail to load properly.
  • Making website content more accessible for people with visual impairments.
  • Increasing website traffic for specific SEO keywords.

To get more details about these advantages, visit this related guide: Why Is Image ALT Text Important for SEO?

Download the SEO Keyword Research CheatsheetDownload the SEO Keyword Research Cheatsheet

How Image ALT Text Works for SEO

Image ALT text works for SEO by providing context to images to inform search engine crawlers about what is displayed in the image to index it correctly in the SERPs. Image ALT text attributes also improve the on-page SEO signals for the content that contains the image.

The process for image ALT text consists of creating alternative content in the form of text that displays in place of images when users view your page with a text-only web browser or when the images fail to load.

Google’s algorithm uses all the data it can find on web pages to determine the overall rankings in the search engine results pages, and well-written ALT text tags offer robust SEO data that can significantly improve the chance an image—and the associated page—has of appearing at the top of the search results for relevant queries.

A deeper explanation of the ALT text process can be found here: How Does Image ALT Text Work for SEO?

Best Practices for Image ALT Text

To get the most value out of image ALT text for SEO, you can follow these best practices:

  • Include the Target SEO Keyword: Putting a target keyword into an image ALT text attribute increases the keyword prominence for search engine optimization.
  • Front-Load the Keyword Phrase: Ranking algorithms assign additional SEO weight to the keywords that are discovered at the beginning of certain HTML elements, including the image ALT attribute. Placing your keyword at the front of this field can improve that SEO signal.
  • Keep Image ALT Text Short: A good practice is to limit the length of your ALT text to 150 characters or fewer. The shorter it is, the better for SEO.
  • Don’t Include Unnecessary Words: Do not include words like “image of” or “picture of” in the ALT text attribute. It dilutes the keyword prominence signals and is redundant for screen readers.
  • Describe the Image Accurately: This practice is important for meeting web accessibility standards and requirements for ADA compliance. Describe the image accurately while also working in your target SEO keyword.
  • Use Empty ALT Text When Necessary: Not all images need optimized ALT attributes. Purely decorative images can have empty ALT text if they’re not necessary for the user to understand the context of the page.
  • Optimize One Image ALT Text Per Keyword: Never repeat the same keyword in other image ALT text attributes. Only one target keyword phrase for the page per ALT attribute is sufficient for Google to make the correct associations for on-page SEO. It also helps you avoid keyword stuffing, which can cause a ranking penalty.
  • Match ALT Text to the Image Filename: Naming the image filename with the same exact match keyword as the target ALT text can help improve optimization by verifying these two SEO signals with each other. Use dashes (-); not underscores (_), to separate the individual words in the image filename.

If you want to learn more about these optimization tips, see the complete guide on How to Optimize Image ALT Text for SEO.

Difference Between Image ALT Text and Title Text

Image ALT text and title text are often confused with each other when it comes to search engine optimization, so it’s good to understand the difference.

The main difference between image ALT text and title text is that image ALT text is used to specify information about images for screen readers and search engines while title text is displayed as visible text when a user hovers over an HTML element.

The comparison table below expands on these key differences so you know how each element applies to SEO and the user experience.

ParameterImage ALT TextTitle Text
Primary PurposeTo accurately describe the content of an image for screen readersTo specify extra information about an HTML element to improve the user experience
Secondary PurposeTo inform search engine crawlers about the content of an image for indexing and rankingsNone
Character LimitNone; but 150 or less is recommendedNone; but 140 or less is recommended
SEO Ranking FactorYesYes; but very slight

Note: A detailed comparison of text title and ALT text attributes can be found here: Image ALT Text vs Title Text In SEO.

Image ALT Text In SEO Summary

I hope you enjoyed this guide on image ALT text in SEO.

As you discovered, image ALT text is alternative text for images that describes the content of the image as it relates to the web page or document. Image ALT attributes are also used by screen reader software and crawled by search engine spiders to index images in the search engine results pages.

Knowing how image ALT text works and ways to improve it for SEO (as explained on this page) can help increase the rankings and traffic for your content in search engines like Google, Yahoo, and Bing.