Image Alt Text: Why It Still Matters for SEO and AI

TL;DR: Alt text is the short description you add to an image so search engines, screen readers, and AI can tell what it shows. It is a basic SEO and accessibility habit that matters more now: many crawlers and AI tools read your page as text, so an image with no alt text gives them far less to go on. Newer AI can look at images, but only when the image is actually handed to it, which most web crawling does not do.

Alt text is one of the smallest things on a web page, and one of the easiest to skip. It is also how machines tell what your images show. A screen reader reads it aloud, Google uses it to understand and rank your images, and text-based AI tools lean on it too. That makes it one small piece of being read and recommended by AI.

Here is the part people get wrong today. AI can look at images now, so it seems like alt text should be obsolete. But an AI model only sees an image when something actually feeds that image into it, and many of the systems that crawl and index the web read your page as text and skip the pixels. In that text, an image is only as clear as the words attached to it.

For any site, that is a real gap. Your best proof often lives in pictures: a product photo, a screenshot, a chart, or Open Graph images. This guide explains what alt text is, why it helps both SEO and AI, and how to write it well, including for complex images like charts and dashboards. It complements titles and meta descriptions, which do similar representational work for the page itself.

How search engines and AI read your images

Whether an AI can see your image depends less on the model and more on how the system reached your page.

When a crawler visits, it mostly pulls out the text. That text is what search engines index and what AI tools later read to answer questions. If an image's meaning never appears in text, those systems have far less to go on when they index and rank it.

In the text version of your page, an image shows up as a few things: its alt text, its filename, a caption, and the words around it. Alt text is the one you fully control, and the one built for exactly this. Without it, a crawler might know there is a file called dashboard.png, and nothing about what the dashboard shows.

Running image recognition on every picture is possible, but it is slower and costlier than reading text, so many systems skip it or do it selectively. Even Google, which does analyze images, still counts alt text among the signals it uses to understand them, per Google's image documentation. That reaches AI answers too: Google AI Mode and AI Overviews are built on Google Search, so the same signals Google reads from your page, alt text included, can help it understand your images, even if Google does not publish exactly how much each one counts. The honest position for 2026: some systems can see your images, many will not bother, and alt text is the reliable text representation that works either way.

What alt text actually is

Alt text is the alternative text on an image, written as the alt attribute of an <img> tag. It was built for accessibility, so that screen readers can describe an image to someone who cannot see it, and it also shows when an image fails to load.

<img src="/images/dashboard.png" alt="Analytics dashboard showing trial signups, activation rate, and churn risk by account segment" />

Its first job is people. Text alternatives for non-text content are a baseline accessibility requirement under WCAG (success criterion 1.1.1, Non-text Content), and the W3C's alt decision tree is the standard guide for what to write. Its second job, the one this article is about, is machines: search engines and text-first AI systems read the alt attribute to understand what an image contains.

Why this matters for your site

Most sites lean on images to make their case. A product photo, a screenshot, a chart, or a diagram often carries the real proof. When those carry no alt text, the exact thing you are using them to demonstrate is the thing a text-based crawler cannot read.

Think about a page that shows something concrete: a product in use, a before-and-after, a chart of results, a floor plan. A person sees it instantly. A text crawler sees an image file with no description, and your strongest evidence contributes little to how many text-first search and AI systems understand the page. Alt text turns that visual proof into indexable, quotable text.

How to write good alt text

The goal is a short, specific description of what the image shows and what it is for. The W3C decision tree gives the rule for each case.

For an informative image, describe the essential information in a sentence. Be specific, not generic.

<!-- Weak -->
<img src="/images/dashboard.png" alt="Dashboard" />

<!-- Better -->
<img src="/images/dashboard.png" alt="Analytics dashboard showing signups, activation rate, churn risk, and revenue by customer segment" />

For a functional image, one used as a link or a button, describe the action, not the picture.

<img src="/icons/download.svg" alt="Download the pricing PDF" />

For a purely decorative image that adds nothing to meaning, use empty alt so assistive tech and parsers skip it. Leaving the attribute off entirely is not the same thing.

<img src="/images/abstract-gradient.svg" alt="" />

A few habits keep alt text useful:

• Be specific to the content. "Black leather ankle boots with a side zip and block heel" beats "product photo," and "webhook settings screen with the URL field and Save button" beats "screenshot."
• Do not start with "image of" or "picture of." The context already knows it is an image.
• Do not keyword-stuff. Cramming search terms reads badly to a screen reader and can look like spam.
• Give files real names. lead-routing-rules.png is a better signal than screen-12-final.png.
• Keep it concise. One clear sentence usually beats a paragraph.

Complex images: charts, dashboards, and diagrams

Some images carry more than one sentence can hold. A chart has a trend and numbers, a dashboard has several panels, and a diagram has a flow. Two moves handle these well.

First, let the alt text carry the key message, not every data point.

<img src="/charts/conversion.png" alt="Line chart showing demo conversion rising from 2.1% to 3.8% after adding intent-based CTAs" />

Second, put the detail in nearby text, a caption or a paragraph, so both people and machines get the full picture:

After intent-based CTAs were added, demo conversion rose from 2.1% in January to 3.8% in March, with the largest lift from returning visitors at target accounts.

That surrounding text is readable by every crawler and screen reader, it helps accessibility, and it means the substance of your chart is in words, not locked in pixels.

What is certain, and what is not

Keep the claims honest.

The certain wins are accessibility and image search. Alt text is a standards-based accessibility requirement, and Google uses it to understand images. Those benefits do not depend on any prediction about AI.

The AI benefit is strong but not guaranteed. Many AI crawlers and retrieval systems read text and represent your images through alt text, so writing it well makes those images legible to them. Whether a given system also runs a vision model on your image varies by product and is not something you control. Alt text is the lightweight, durable representation that works regardless, which is why it is worth doing even as vision models improve.

Common mistakes to avoid

• Shipping important screenshots and charts with no alt attribute at all.
• Writing vague alt like "dashboard" or "chart" that describes nothing specific.
• Starting every alt with "image of," which wastes the first words.
• Keyword-stuffing alt text, which hurts accessibility and can read as spam.
• Adding descriptive alt to purely decorative images instead of using alt="".
• Leaving the real detail of a chart only in the picture, with no caption or nearby text.

Where SupaIntent fits

Good alt text makes your images legible to search and text-first AI. It does not tell you whether AI systems actually describe your product correctly, which competitors they recommend, or which of your pages they pull from. Seeing that requires measuring your real presence across ChatGPT, Gemini, Perplexity, and Google AI Mode. That is what SupaIntent does, a low-lift way to start improving your AI visibility.

FAQ

Do I still need alt text if AI can see images?

Yes. AI models can look at an image, but only when the image is actually passed to them. Many crawling and indexing systems read a page as text, where an image is represented by its alt text, filename, and nearby copy. Without alt text, those text-first systems get almost nothing from your images.

What is alt text for?

Alt text is the alt attribute on an image. Its first purpose is accessibility, so screen readers can describe images to people who cannot see them, and it shows when an image fails to load. It also helps search engines and text-based AI systems understand what an image contains.

How do I write good alt text?

Describe what the image shows and what it is for, in one specific sentence. Do not start with "image of," do not keyword-stuff, and use empty alt (alt="") for purely decorative images. For functional images used as links or buttons, describe the action rather than the picture.

How should I handle charts and dashboards?

Let the alt text carry the key message, like the trend a chart shows, rather than every number. Then put the full detail in a nearby caption or paragraph, so both people and machines can read the substance instead of it being locked in the image.

Does alt text help SEO?

Yes, for image search. Google uses alt text, along with computer vision and page content, to understand images, and descriptive alt improves image search relevance. Avoid keyword stuffing, which can work against you.

Your product screenshots, charts, and diagrams are often your best evidence. To a person, they land instantly. To a text-first crawler, they are only as visible as the words you attach to them. Alt text is a small, durable way to make sure the proof you put in pictures is proof a machine can actually read.