The Complete Guide to Alt Text: Accessibility, SEO, GEO and AI Search Optimization

I’ve reviewed thousands of images with missing or poorly written alt text. The impact goes far beyond accessibility compliance—it affects search rankings, AI-generated summaries, and whether real people can actually use your website.

Let me share what actually matters when it comes to alt text, and why getting it right benefits everyone who interacts with your site.

Why Alt Text Matters More Than Ever

Alt text (alternative text) serves three critical audiences:

People using screen readers rely on alt text to understand image content. Without it, they encounter silent gaps in your content—imagine reading an article where random sentences are deleted.

Search engines use alt text as primary context for image indexing. Google can’t “see” images the way humans do. Your alt text tells search engines what’s in the image and how it relates to surrounding content.

AI systems (including ChatGPT, Perplexity, and Google’s AI Overviews) increasingly reference and cite web content. Well-written alt text helps these systems accurately represent your images and content when generating responses to user queries. While AI can understand some image content on it’s own, the results are often inaccurate and misleading.

The SEO Advantage You’re Missing

Many organizations treat alt text purely as an accessibility checkbox. That’s leaving engagement on the table.

Image search drives significant traffic. Google Images accounts for over 20% of all web searches. Sites with comprehensive, descriptive alt text appear more frequently in image search results.

Alt text provides contextual signals that help search engines understand your page topic and relevance. When your alt text aligns with your content strategy and target keywords (without keyword stuffing), it reinforces topical authority.

Modern search ranking factors increasingly consider user experience signals. Screen reader users who can fully comprehend your content spend more time on your site and engage more deeply—signals that search algorithms reward.

AI Search and the Future of Discoverability

Here’s what many organizations haven’t considered yet: AI search systems are fundamentally changing how content gets discovered and cited.

When someone asks ChatGPT or Perplexity about a topic your site covers, these systems scan and synthesize web content. Sites with comprehensive alt text get more accurately represented in AI-generated responses.

Google’s AI Overviews now appear at the top of many search results. These AI-generated summaries pull from indexed content—including image descriptions. If your images have clear, descriptive alt text, they’re more likely to be referenced when AI systems generate summaries about your topic.

Think of alt text as making your content “AI-readable.” Just as screen readers need text descriptions of visual content, AI systems use alt text to understand and reference your images accurately.

The Core Alt Text Rules

Let’s cut through the confusion. Here’s what you actually need to know:

Rule 1: Describe What Matters for Context

Write alt text that conveys why the image is there and what information it communicates.

Bad: “Image123.jpg” Bad: “A photo” Good: “Dashboard showing website accessibility score of 87/100 with breakdown of issues by severity”

Ask yourself: If I removed this image and only left the alt text, would readers understand what they’re missing?

Rule 2: Keep It Concise But Complete

Screen readers announce “image” before reading alt text, so don’t start with “image of” or “picture of.” Get straight to the description.

Aim for 125 characters or less when possible. Some screen readers cut off longer alt text. If you need more detail, put it in surrounding text or captions.

Too short: “Chart” Better: “Bar chart comparing average page load times across five website builders”

Rule 3: Consider Context and Surrounding Content

Don’t repeat information already in surrounding text. Alt text should complement nearby content, not duplicate it.

If your heading says “Q4 Revenue Exceeded Projections,” and your image is a graph showing that data, your alt text might be: “Bar graph showing 24% revenue increase from Q3 to Q4” rather than repeating what the heading already communicates.

Special Cases: Decorative Elements

Here’s where people get confused. Not every image needs descriptive alt text.

Decorative images that don’t convey meaningful information should have empty alt attributes: alt=””

This tells screen readers to skip the image entirely—which is exactly what you want for purely decorative elements.

Examples of decorative images:

• Background patterns
• Decorative borders or dividers
• Icons used purely for visual design (not functional buttons)
• Spacer images
• Generic stock photos that don’t add information

The test: If removing the image wouldn’t change a user’s understanding of your content, it’s probably decorative.

Logo Best Practices

Logos require special consideration because they serve multiple purposes on websites.

Logo in Header (General Appearance)

For a logo that appears in your header but doesn’t link anywhere:

alt=”[Company Name]” or alt=”[Company Name] logo”

Simple and direct. It identifies your brand without unnecessary detail.

Logo Linking to Homepage

When your logo links to your homepage (the most common pattern):

alt=”[Company Name] home” or alt=”Return to [Company Name] homepage”

This tells screen reader users both what they’re clicking on AND what it does. Clarity matters more than brevity here.

Important: Don’t leave logo links with empty alt text (alt=””). That creates a confusing experience where screen reader users encounter an unlabeled link—they’ll hear “link” with no information about where it goes.

Logo in Footer

If you have a logo in your footer that also links home:

alt=”[Company Name]” is typically sufficient

Users have likely already encountered and understood your main navigation by this point.

Functional Images vs. Informational Images

Understanding this distinction prevents common mistakes.

Functional images are interface elements people interact with. Your alt text should describe the action, not appearance.

• Search icon button: alt=”Search” not alt=”Magnifying glass icon”
• Shopping cart: alt=”View cart” not alt=”Shopping cart icon”
• Edit button: alt=”Edit profile” not alt=”Pencil icon”

Informational images convey content. Describe what information they provide.

• Product photo: alt=”Blue canvas backpack with leather straps and front zipper pocket”
• Screenshot: alt=”WordPress dashboard showing published posts sorted by date”
• Infographic: Summarize key data points, or use long description techniques for complex graphics

Complex Images: Charts, Graphs, and Infographics

When images contain multiple data points, you have several options:

Option 1: Concise Alt + Detailed Caption

Use alt text for a brief summary, then provide full data in a visible caption or surrounding text.

alt=”Line graph showing steady increase in mobile traffic from 2020-2024″

Then include actual data points in caption text visible to everyone.

Option 2: Link to Text Alternative

For particularly complex graphics:

alt=”Accessibility compliance workflow diagram—detailed description available” with a link to a text description.

Option 3: Use Tables or Lists

If your infographic presents data, consider also presenting that data in an accessible table format elsewhere on the page.

Common Alt Text Mistakes to Avoid

Keyword stuffing: Don’t cram keywords into alt text for SEO. Search engines recognize this and it creates terrible user experience.

Redundancy: If your image is purely decorative or duplicates surrounding text exactly, use empty alt text.

Being overly artistic: Alt text isn’t creative writing. Be clear and functional.

Forgetting about context: An image of a dog might need very different alt text depending on whether it appears in a veterinary article, a product listing for dog food, or a blog post about pet adoption.

Using filenames: “IMG_4829.jpg” tells users nothing. Always write actual descriptions.

The Business Case for Better Alt Text

Beyond compliance requirements, comprehensive alt text delivers measurable benefits:

• Improved search visibility leading to increased organic traffic—especially from image search
• Better AI search representation as these systems become more prominent in how people discover content
• Enhanced user experience for everyone, not just screen reader users
• Stronger SEO foundation through better content context and topical relevance
• Reduced legal risk from accessibility complaints

Organizations that treat alt text as a strategic content component rather than a compliance checkbox consistently see better results across all these metrics.

Making Alt Text Part of Your Workflow

The biggest challenge isn’t understanding alt text rules—it’s implementing them consistently across your entire site.

For new content: Train content creators and designers to write alt text as they add images. Make it a required field in your CMS if possible.

For existing content: Use accessibility scanning tools to identify images with missing or inadequate alt text, then systematically improve them.

For WordPress sites: Tools like Insi can automatically scan your entire site to flag alt text issues, including images missing alt attributes entirely, alt text that’s just filenames, or decorative images that should have empty alt attributes.

The key is making alt text visible and measurable—not hoping people remember to add it.

The Path Forward

Alt text is one of those rare opportunities where doing the right thing for accessibility also benefits your SEO, makes your content more discoverable by AI systems, and improves user experience for everyone.

The organizations that prioritize comprehensive, well-written alt text across their digital properties will increasingly have an advantage as AI search systems become more prominent and as accessibility requirements continue tightening.

Start with your highest-traffic pages. Fix missing and inadequate alt text there first. Then work systematically through your site. The investment in time pays dividends across multiple business objectives.