Alt Text for SEO: How to Optimize Your Images

Alt text (alternative text) is a short description of an image written into the HTML code of a web page. Visitors don’t see it unless the image fails to load, but screen readers, search engines, and increasingly AI models all rely on it to understand what an image shows.

Here is what a basic alt attribute looks like in HTML:

<img src="keyword-research-dashboard.png" alt="keyword research dashboard showing search volume and difficulty metrics">

The text inside the alt="" attribute is the alt text. It lives in the code, not on the visible page.

Despite being invisible to most visitors, alt text plays an outsized role in how your content performs. It influences accessibility, organic rankings, image search traffic, and — as we’ll cover later — how AI models interpret and cite your pages.

In this article, you’ll learn what alt text is, why it matters for both SEO and AI search visibility, how to write it well, and how to audit your existing images so every page on your site works harder for you.

Why Alt Text Matters

Alt text serves five distinct purposes. Each one is a reason to get it right.

1. It makes your site accessible

Roughly 2.2 billion people worldwide have some form of vision impairment. Many use screen readers — tools that convert on-screen content to audio — to navigate the web.

When a screen reader hits an image without alt text, it either skips the image entirely or reads out the filename. Neither is helpful. A filename like IMG_4087.jpg tells a visually impaired user nothing about what the image shows.

Proper alt text solves this. Instead of silence or gibberish, the screen reader describes the image in plain language, keeping the content experience intact.

Beyond courtesy, this is also a legal consideration. The Web Content Accessibility Guidelines (WCAG 2.1) require text alternatives for all non-decorative images. Websites that fail to comply risk lawsuits under accessibility legislation like the ADA in the United States and the European Accessibility Act in the EU.

2. It strengthens topical relevance

Google looks at the words on a page to understand what it’s about. If your page mentions “content marketing,” “editorial calendar,” and “distribution strategy,” Google knows it’s about content marketing.

But sometimes important context is locked inside images that Google can’t fully read.

Consider a blog post about email marketing that includes a screenshot of an email campaign dashboard. Without alt text, Google sees an image file — nothing more. With alt text like “email campaign dashboard showing open rate of 42% and click-through rate of 3.8%,” Google gains additional topical signals that reinforce what the page is about.

Google’s own documentation confirms this. Their Search Central guidelines state that alt text helps them understand the subject matter of an image and how it relates to the surrounding content.

This is especially important for pages targeting competitive keywords. Every signal that reinforces your page’s relevance — including alt text — can be the difference between ranking on page one and ranking on page two.

3. It helps you rank in Google Images

Google Images is the second-largest search engine in the world. It accounts for over 20% of all web searches, putting it ahead of YouTube, Bing, and every other search engine combined.

That means Google Images is a real traffic channel — not just a place people browse for wallpapers.

Google’s John Mueller has said directly that alt text is critical for ranking in Google Images. If you want your images to appear in image search results, alt text is one of the primary signals Google uses to determine relevance.

The opportunity here depends on your niche. Visual industries like fashion, food, interior design, and e-commerce see significant traffic from image search. Even for less visual niches, every click from Google Images is incremental traffic you’d otherwise miss.

4. It acts as anchor text for image links

Anchor text is the clickable text in a hyperlink. Google uses it to understand what the linked page is about.

When you use an image as a link instead of text, there’s no visible anchor text for Google to read. In that case, Google treats the image’s alt text as the anchor text.

Here’s what that looks like in HTML:

<a href="/blog/keyword-research-guide">
  <img src="keyword-research.png" alt="complete guide to keyword research for SEO">
</a>

In this example, “complete guide to keyword research for SEO” functions as anchor text. It tells Google what the linked page is about, the same way clickable text would.

This matters most for internal linking. If your site navigation, sidebar, or in-content links use images (logos, banners, thumbnails), the alt text on those images directly affects how Google understands your internal link structure.

5. It influences how AI models understand your content

This is the reason most guides on alt text miss entirely.

AI search engines like ChatGPT, Perplexity, Claude, and Gemini don’t just crawl your text — they build a contextual understanding of your entire page. Alt text contributes to that understanding by providing context that the surrounding paragraph alone might not convey.

When an AI model processes a page about “best project management tools” and encounters an image with alt text reading “Asana dashboard showing task assignments and project timeline,” it now has a concrete data point. That specificity makes the page more likely to be cited when someone asks an AI model a related question.

Think of it this way: AI models are trying to determine which pages are the most comprehensive and authoritative sources on a topic. Pages with well-described images signal depth. Pages with missing or generic alt text signal shallow coverage.

This is especially relevant for pages that include screenshots, data visualizations, comparison charts, or product interfaces — the types of images that carry real informational value.

You can track whether your pages are being cited by AI models using Analyze AI’s Sources dashboard. It shows every URL that AI platforms reference when answering questions in your industry, along with which models cite each page and how often.

If you notice that pages with thorough alt text get cited more frequently, that’s a pattern worth doubling down on. You can dig deeper into the specific URLs being cited and which brands are mentioned alongside yours using the URL-level view.

How to Add Alt Text to Images

Adding alt text is straightforward. The exact steps depend on whether you’re working in HTML or a CMS.

In HTML

Add an alt attribute to the <img> tag:

<img src="seo-audit-checklist.png" alt="SEO audit checklist with 15 on-page factors">

That’s it. The alt attribute is all you need. Keep the description concise, accurate, and relevant to the page’s content.

In WordPress

WordPress has a built-in alt text field. When you upload or select an image in the media library, you’ll see an “Alt Text” field on the right side of the screen. Type your description there, and WordPress writes it into the HTML for you.

You can also add alt text directly in the block editor. Click on an image block, then look for the alt text field in the block settings panel on the right.

In Shopify

In Shopify, you add alt text through the product editor or the content editor. Click on any image, select “Edit alt text” (or the pencil icon), and type your description.

In Squarespace

In Squarespace, click on any image block, then look for the image settings or the “Design” tab where you can enter alt text.

In other CMS platforms

Most modern content management systems — Webflow, Wix, Ghost, HubSpot — have a dedicated alt text field for images. The exact location varies, but the principle is the same: find the image settings, locate the alt text field, and write a clear description.

If your CMS doesn’t have a dedicated field, you can usually add alt text through the HTML editor or by editing the page’s source code.

Should You Add Alt Text to Every Image?

No. This is a common misconception that actually hurts accessibility when done wrong.

Some images are purely decorative. They don’t carry information, and they don’t contribute to the page’s content. Adding alt text to these images creates noise for screen reader users and provides no SEO value.

Here are the types of images that should not have descriptive alt text:

Decorative icons and dividers. Small icons used to separate sections, bullet point graphics, or visual flourishes exist only for aesthetics. Describing them to a screen reader user adds no value. It’s the equivalent of narrating every period and comma in a sentence.

Generic stock photos. A stock photo of smiling business people in a conference room on a page about project management doesn’t add information. Describing it as “group of professionals in a meeting” is meaningless to a visually impaired reader because it tells them nothing they need to know.

Background images and textures. These are visual design elements, not content.

The empty alt attribute

For decorative images, the correct approach is to use an empty alt attribute — not to remove the alt attribute entirely.

<!-- Correct: empty alt attribute for decorative images -->
<img src="decorative-divider.png" alt="">

<!-- Wrong: missing alt attribute entirely -->
<img src="decorative-divider.png">

The difference matters. When a screen reader encounters an image with no alt attribute at all, some readers will try to read the filename instead — which leads to a terrible user experience. An empty alt attribute tells the screen reader to skip the image entirely.

Images that always need alt text

On the other hand, these types of images should always have descriptive alt text:

Screenshots. Whether it’s a tool interface, a settings panel, or a code editor, screenshots carry information that the surrounding text often references. Without alt text, a screen reader user loses that context entirely.

Charts and data visualizations. If your page shows a bar chart of quarterly revenue, the alt text should describe the key takeaway: “bar chart showing Q3 revenue at $4.2M, up 18% from Q2.”

Product photos. Every product image on an e-commerce site needs alt text. It’s both an accessibility requirement and an SEO opportunity — product-specific alt text helps images appear in Google Shopping and image search.

Infographics. These pack a lot of information into a visual format. The alt text should summarize the key points, not attempt to describe every visual element.

Logos used as links. If a logo links to a homepage or a partner site, the alt text should describe the destination, not the visual. For example: “Analyze AI homepage” rather than “teal and white logo.”

How to Write Good Alt Text

Writing effective alt text comes down to five principles. None of them are complicated, but applying them consistently across hundreds or thousands of images takes discipline.

1. Be specific and concise

Good alt text describes the image clearly in as few words as possible. Aim for one sentence or a short phrase. Most screen readers cut off alt text around 125 characters, so brevity helps usability too.

Vague: “chart”

Specific: “line chart showing organic traffic growth from 10K to 45K monthly visits over 12 months”

The second example tells you exactly what the chart shows. The first tells you nothing.

2. Describe what the image communicates, not what it looks like

This is the most common mistake. Many people describe the visual appearance of an image — its colors, layout, composition — when they should be describing the information it communicates.

Ask yourself: if someone couldn’t see this image, what would they need to know to follow the rest of the page?

For a screenshot of a Google Analytics dashboard, the answer isn’t “screenshot with a white background and blue sidebar.” The answer is “Google Analytics traffic report showing 50,000 sessions with 65% from organic search.”

3. Include relevant keywords — naturally

Alt text is a legitimate place to include keywords, but only when they fit naturally. Google explicitly warns against keyword stuffing in alt text, and screen readers will read the alt text aloud — so unnatural phrasing is immediately obvious.

Keyword-stuffed: “SEO tools best SEO tools free SEO tools keyword research SEO software”

Natural: “keyword research results in an SEO tool showing search volume and ranking difficulty”

The second example includes “keyword research” and “SEO tool” naturally because those terms accurately describe the image. The first example is spam.

A good rule of thumb: if the alt text would sound awkward read aloud, rewrite it.

4. Don’t start with “image of” or “picture of”

Both Google and screen readers already know it’s an image. Starting your alt text with “image of” or “photo of” wastes characters on information that’s already understood.

Redundant: “Image of a woman typing on a laptop”

Better: “Woman typing a blog post on a laptop in a coffee shop”

The one exception: if the type of image matters for context. For example, “oil painting of a pastoral landscape” — here, “oil painting” adds meaningful information about the medium.

5. Match the context of the page

The same image can have different alt text depending on where it appears.

A photo of a golden retriever on a pet adoption page might have alt text: “adoptable golden retriever, 3 years old, named Buddy.” On a veterinary health blog, the same photo might warrant: “golden retriever showing healthy coat and bright eyes after regular grooming.”

The image is the same. The context — and therefore the useful description — changes.

This principle is especially important for images used across multiple pages. Don’t copy-paste the same alt text everywhere. Tailor it to what the page is about.

Alt Text Examples: Good vs. Bad

Let’s walk through concrete examples across different image types so you can see these principles in action.

Example 1: Product photo

Imagine a photo of a pair of running shoes on an e-commerce product page.

Notice how the “best” version includes the model number. For e-commerce, this is critical because people search for specific models in Google Images.

Example 2: Screenshot of a tool

Imagine a screenshot of a keyword research tool showing results for the query “content marketing strategy.”

Example 3: Data visualization

Imagine a bar chart comparing organic traffic across four competitor websites.

Example 4: Decorative image

A stock photo of a sunrise used as a header image on a blog post about morning productivity routines.

How to Find and Fix Alt Text Issues

You now know how to write good alt text. But how do you handle the hundreds (or thousands) of images already on your site?

The answer: don’t try to fix everything at once. Prioritize the pages that matter most and work outward from there.

Step 1: Identify your highest-traffic pages

Start with the pages that already get the most organic traffic. These are the pages with the most visitors — including visually impaired visitors — and the most potential upside from better image optimization.

You can find your top pages in Google Search Console under Performance > Pages. Sort by clicks to see which pages drive the most organic traffic.

If you use an SEO tool like Analyze AI’s Website Traffic Checker, you can also see estimated traffic for any domain — including competitors. This helps you benchmark and prioritize.

Step 2: Audit the alt text on those pages

Install the free Alt Text Tester Chrome extension. Load your highest-traffic page, activate the extension, and hover over each image. The extension shows you the alt text (or warns you if it’s missing) directly on the page.

Check for these issues as you go:

Missing alt text. The image has no alt attribute at all. This is the highest-priority fix — it hurts both accessibility and SEO.

Empty alt text on informational images. An empty alt attribute (alt="") is correct for decorative images, but wrong for screenshots, charts, product photos, or any image that carries information.

Keyword-stuffed alt text. Alt text that reads like a list of keywords rather than a natural description. Google has specifically warned against this.

Generic or vague alt text. Descriptions like “image1” or “photo” that don’t tell anyone — human or machine — what the image actually shows.

Overly long alt text. Descriptions that run to multiple sentences. Keep alt text under 125 characters when possible. If the image requires a longer description (like a complex infographic), use the longdesc attribute or a caption instead.

Step 3: Fix the issues you find

For each issue, write new alt text following the principles covered earlier in this guide. Be specific, be concise, include relevant keywords naturally, and match the context of the page.

In most CMS platforms, you can update alt text directly through the media library or the page editor. There’s no need to touch the HTML unless you’re working on a custom-coded site.

How to prioritize fixes:

If you have dozens of images to fix, start with these in order:

1. Images with no alt attribute at all. These are the worst for both accessibility and SEO. Fix them first.

2. Images on your highest-traffic pages. These pages have the most visitors and the most SEO value at stake.

3. Product images. On e-commerce sites, product photos are the most commercially important images.

4. Images used as links. If the alt text is missing, Google has no anchor text for the link — a direct SEO problem.

5. Screenshots and charts. These carry informational value that’s invisible without alt text.

Step 4: Run a site-wide crawl for missing alt text

Once you’ve fixed your top pages, run a broader audit. A site audit tool can crawl your entire site and flag every image with missing or empty alt text.

Free tools like Analyze AI’s Broken Link Checker can help you identify issues across your site. For a deeper crawl, tools like Screaming Frog or Sitebulb will generate a complete report of every image and its alt text status.

Export the report, sort by page traffic or page importance, and work through the fixes systematically.

Step 5: Check which pages AI models are already citing

Here’s where most alt text guides stop. But if you’re optimizing for both traditional SEO and AI search, there’s one more step.

Check which of your pages AI models are already referencing in their answers. Pages that get cited frequently are pages where content quality — including image descriptions — matters most.

In Analyze AI, the AI Traffic Analytics dashboard shows which pages receive visits from AI platforms like ChatGPT, Perplexity, Claude, and Gemini. If a page is receiving AI referral traffic, it’s being used as a source — and its content quality (including alt text) directly influences whether it continues to be cited.

You can drill down to the individual session level to see exactly which AI platform sent the visitor and which page they landed on.

If you notice that certain pages get high AI referral traffic but have weak alt text, those pages should jump to the top of your optimization list. Improving their alt text strengthens the contextual signals that AI models use to determine whether a page is worth citing.

How Alt Text Fits Into Your AI Search Strategy

Alt text optimization is an SEO fundamental. But it also plays a growing role in how AI models evaluate and cite your content.

Here’s why: AI search engines don’t just rank pages — they read and synthesize them. When a model like ChatGPT or Perplexity generates an answer, it pulls information from source pages and assembles a response. The more context a page provides — through body text, headings, structured data, and alt text — the more useful it is to the model.

Pages with thorough, descriptive alt text give AI models more raw material to work with. Pages with missing or generic alt text leave gaps in the model’s understanding.

This doesn’t mean you need to change how you write alt text. The same principles that make alt text good for accessibility and SEO also make it good for AI search. Be specific, be accurate, include relevant context, and describe the information the image communicates.

What changes is how you measure the impact.

Track your AI search visibility

Traditional SEO tools show you how your pages rank in Google. But they can’t tell you whether AI models are mentioning your brand, citing your pages, or recommending your products.

Analyze AI fills that gap. The Prompts dashboard tracks which prompts mention your brand across ChatGPT, Perplexity, Claude, Gemini, and Copilot. You can see your visibility score, sentiment, position, and which competitors appear alongside you.

Identify competitors winning in AI search

The Competitors view shows which brands AI models mention most frequently in your category. If a competitor consistently appears in AI answers where you don’t, that’s a gap you can close — and content quality, including image optimization, is part of closing it.

Understand how AI models perceive your brand

The Perception Map shows how AI models describe your brand across different topics. If models associate your brand with depth and authority in certain areas, you can reinforce those associations through better content — including better-optimized images.

The key insight is this: alt text optimization isn’t a standalone tactic. It’s part of a broader content quality strategy that affects how both traditional search engines and AI models evaluate your pages. Optimizing your images strengthens every channel simultaneously.

Common Alt Text Mistakes to Avoid

Even experienced SEOs make these errors. Here’s what to watch out for.

Using the same alt text for every image

Some sites — especially e-commerce stores — use identical alt text across hundreds of product images. Every shoe gets “running shoe,” every shirt gets “men’s t-shirt.” This helps neither accessibility nor SEO because it provides no differentiating information.

Every image should have unique alt text that describes what makes it distinct.

Writing alt text for search engines instead of people

If your alt text reads like a keyword list, you’ve optimized for the wrong audience. Google explicitly flags this as a bad practice, and screen readers will read it aloud — making the experience terrible for visually impaired users.

Write alt text for a human who can’t see the image. If it happens to include relevant keywords, great. If it doesn’t, that’s fine too.

Ignoring alt text during site redesigns and migrations

Site redesigns are one of the most common causes of alt text loss. Images get re-uploaded, templates change, and alt text that existed on the old site disappears on the new one.

If you’re planning a redesign or migration, export your current alt text before you start. After launch, run a crawl to verify that every image still has its alt text intact.

Describing images that don’t exist yet

This sounds obvious, but it happens with dynamic content. If your CMS pulls images dynamically (for example, user-generated content or API-driven product feeds), the alt text field often defaults to empty. Build alt text generation into your content pipeline so it’s never an afterthought.

Forgetting about images in emails and social

Alt text isn’t just for your website. Email clients often block images by default, and the alt text is what recipients see instead. Social media platforms use alt text for accessibility too. If you’re only optimizing alt text on your website, you’re missing part of the picture.

Alt Text Checklist

Use this checklist every time you add an image to a page:

Final Thoughts

Alt text is one of the simplest on-page SEO improvements you can make. It takes seconds to write, it costs nothing to implement, and it benefits accessibility, organic search, image search, and AI search visibility all at once.

Most sites still get it wrong. They skip it entirely, stuff it with keywords, or treat it as an afterthought. That’s an opportunity for you.

Start with your highest-traffic pages. Audit the alt text. Fix the obvious gaps. Then work outward.

And as AI search grows alongside traditional search, remember that every piece of context you give AI models — including descriptive alt text — makes your content more useful, more citable, and more visible.

SEO is evolving, not dying. Alt text is one more way to evolve with it.