What it actually is
Alt text is a written description attached to an image in your HTML. It exists so that anyone who cannot see the image still gets the information the image carries.
That is the whole idea. Everything else follows from it.
Three groups rely on it. People using screen readers, who hear the description read aloud. Anyone whose image failed to load, on a bad connection or in an email client that blocks images. And machines, which cannot see your page the way you do.
The objection worth addressing first
Vision models can describe images now. Reasonably well. So a fair question is whether alt text has become busywork.
It has not, and the reason is specific.
A model can tell you an image shows a man in a suit standing at a podium. It cannot tell you that the man is your founding partner, that the podium is in a Clark County courtroom, or that the image links to your litigation services page. It describes what is in the frame. It does not know what the image is doing on your page.
A vision model sees the picture. Alt text explains why the picture is there. Those are different jobs and only one of them can be automated.
Use AI to draft alt text if you have hundreds of images. That is a genuinely good use of it. But somebody has to check the output, because the model cannot know your context, your terminology, or whether an image is decorative or functional.
The legal position, stated plainly
This is not a theoretical risk.
An investigation by Cox Media Group counted more than fifteen thousand ADA website lawsuits filed in four years, with about ninety percent originating from sixteen law firms. Missing alt text is the most commonly cited violation in those complaints, because it is trivial to detect with an automated scan.
That is the mechanic worth understanding. Nobody is browsing your site looking for problems. A tool crawls thousands of sites, flags the ones with obvious failures, and generates a list. Missing alt text puts you on that list.
The reference standard is WCAG, specifically Success Criterion 1.1.1, which requires a text alternative for non decorative content. Courts have used WCAG as the benchmark for over a decade even though the ADA itself does not name it.
Two dates worth knowing. The Department of Justice rule requiring state and local governments serving populations above fifty thousand to meet WCAG 2.1 Level AA took effect April 24, 2026. And the European Accessibility Act became enforceable in June 2026, carrying fines that run from twenty thousand to two hundred fifty thousand euros.
If you sell to European customers or contract with public agencies, those apply to you directly.
Why it also earns you traffic
Google states in its own image guidelines that alt text is the primary signal for understanding what an image shows. Roughly a quarter of all Google searches happen in Google Images, and far more than that in visual categories like food, apparel, and home goods.
There is a second effect people miss. When an image is wrapped in a link, its alt text functions as the anchor text for that link. If your call to action is an image with no alt text, you have handed Google a link with no description of where it goes.
And AI search systems now use the same signal. When an assistant pulls an image into an answer, it is reading alt text to decide the image is relevant. Vague or missing descriptions make your images invisible to that retrieval, exactly as they are invisible to a screen reader.
How to write it
The test is simple. If you read only the alt text aloud, would the listener get what the image contributes to the page?
- 01Describe the content, not the file. "Golden retriever catching a frisbee at Sunset Park" beats "dog photo"
- 02Keep it under about one hundred twenty five characters. Screen readers truncate beyond that
- 03Skip "image of" and "photo of". The screen reader already announced it is an image
- 04Include a keyword only when it belongs there naturally. Stuffing hurts both rankings and the person listening
- 05For a linked image, describe the destination rather than the picture
- 06For a chart, give the takeaway. "Revenue grew from forty thousand to one hundred ten thousand across four quarters", not "bar chart"
- 07For a photo of text, transcribe the text
- 08For a decorative image that adds nothing, use an empty alt attribute
An empty alt attribute is not the same as a missing one. Writing alt="" tells a screen reader to skip the image deliberately, which is correct for background flourishes and spacer graphics. Omitting the attribute entirely leaves the software guessing, and some will read the file name aloud instead. Your visitor hears "I M G underscore four eight two one dot j p g." Empty is a decision. Missing is an accident.
The mistakes that show up most
- Using the file name as alt text, which is what happens automatically in several page builders
- The same alt text on every image, usually the business name
- Keyword stuffing, which now trips Google spam filters as well as annoying listeners
- Describing a chart as a chart rather than saying what it shows
- Treating a caption as a substitute. Captions are visible to everyone; alt text is for people who cannot see the image. They are not interchangeable
- Assuming an accessibility overlay widget fixes it. Overlays do not repair the underlying markup, and courts have not accepted them as a defense
Where to start if your site is already built
Do not try to fix everything at once. Work in this order.
- 01Run a free scan and get the actual count of images missing alt text
- 02Fix your home page first, since it is what an automated audit hits first
- 03Fix your top five pages by traffic next
- 04Fix anything in a conversion path: product images, form graphics, buttons built as images
- 05Mark decorative images with an empty alt attribute rather than describing them
- 06Then work backward through older content as you have time
- 07Add alt text to your publishing checklist so the problem stops growing
Old blog posts count. They are part of your public website and an audit will not skip them because they are old.
What this actually costs
For a typical first year business website with forty or fifty images, this is an afternoon. Maybe two.
Set against that: it removes the most commonly cited violation in a category of lawsuit that has grown every year since 2017, it makes your images eligible for image search and for AI answers, and it means a person using a screen reader can actually use the site you paid to build.
There are very few things on a website where the effort is that small and the argument is that one sided.