A short description added to an image’s HTML attribute that conveys the image’s content and purpose.
Web developers, SEO specialists, and accessibility experts read this when optimizing images on a webpage.
01How alt text works
Alt text is supplied through the alt attribute on an element. When a search engine crawls the page, it reads this attribute to understand what the image depicts and how it relates to surrounding text. Assistive technologies, such as screen readers, read the alt text aloud to users who cannot see the image, providing equivalent information. If the image fails to load, the browser displays the alt text in its place.
Alt text is a simple text label for an image that tells both people and machines what the picture shows, without requiring the user to see it.
02What to do this week
Audit all images on your site this week. For each image, write a concise description that conveys its purpose and content, aiming for under 125 characters. Leave the alt attribute empty (alt='') for purely decorative images. Avoid repeating the file name or stuffing keywords. Update the HTML or CMS fields accordingly and republish.
03How to notice or measure alt text
Inspect the alt attribute using browser developer tools: right‑click an image, choose Inspect, and verify the alt value. Run a site crawl with tools like Screaming Frog or Sitebulb to list images missing alt text. In Google Search Console, check the Enhancements > Images report for warnings. Lighthouse audits also flag missing or poor alt text.
04Common mistakes
- Using generic phrases like "image" or "photo"
- Repeating the file name instead of describing content
- Stuffing keywords to manipulate rankings
- Leaving alt blank for informative images
- Using the same alt text for multiple different images
05When alt text does not apply
Alt text is meant for images that convey information. It is not needed for images that are purely decorative, for which an empty alt attribute (alt='') is appropriate. Background images defined via CSS do not use the alt attribute at all. The term is sometimes confused with the image title attribute or a caption, which serve different purposes and are not read by screen readers in the same way.
06Worked example
Here is a typical implementation:
<img src='puppy.jpg' alt='Golden retriever puppy playing in grass'>
Frequently asked questions
How is alt text different from the image filename or file metadata?
Alt text is the value placed in the HTML alt attribute on an <img> element, while the filename is part of the image's URL and metadata lives inside the image file itself. Search engines read the alt attribute first and treat it as the authoritative description of the image, falling back to metadata only when the attribute is missing.
Do I need to add alt text to every image on my site?
Yes, every informative or functional image should have an alt attribute, but the value depends on the image's role. Decorative images that add no meaning should use an empty alt attribute (alt="") so screen readers skip them, while images conveying content need a concise, descriptive value.
How do I actually add or edit alt text on an existing image?
Open the page in a browser, right-click the image and choose Inspect, then locate the <img> tag in the developer tools and edit or add the alt attribute directly. In most content management systems you can update alt text through the image properties dialog without touching code.
Does alt text still matter for SEO now that search engines can analyze images?
Yes, alt text remains one of the strongest on-page SEO signals for image search and overall page relevance. Search engines still rely heavily on the alt attribute because automated image recognition is not yet reliable enough to replace it.
What happens if I write bad or missing alt text?
Missing or poorly written alt text reduces your image's chances of appearing in search results and can hurt overall page rankings. You'll notice the drop through lower image-search traffic and, if you use accessibility tools, an increase in screen-reader usability issues.
How quickly will I see results after fixing alt text?
Search engines typically recrawl and reindex updated alt text within a few days to several weeks, depending on site authority and crawl frequency. Meanwhile, you can measure progress by monitoring image-search impressions and clicks in your search console.
Asked out loud
spoken, not typedThe same term in the words somebody uses speaking to an assistant rather than typing into a box — written from the situation, which is why each one carries the situation it came from.
Use your CMS's bulk-edit or media-library feature to add alt text to multiple images at once, or enable a plugin that prompts for alt text on upload. If you're on mobile, most platforms let you edit image settings from the media tab without switching to desktop.
Yes, missing or empty alt attributes are a common reason images get dropped from image search. Check the <img> tags in the page source and add concise, relevant alt text that describes what's in each photo.
It's a missed SEO and accessibility opportunity, but it's easily fixable. Audit your existing images, add descriptive alt text that matches the content and purpose of each image, and set a team reminder to fill it in on future uploads.