Alt Text: Essential Guide for Image Accessibility and SEO

In a world where visual content dominates digital spaces, we often overlook a simple yet powerful HTML attribute that makes all the difference—alt text. For the over 2.2 billion people worldwide with some form of vision impairment, properly implemented alt text isn’t just helpful—it’s essential. Meanwhile, according to a 2023 study by Backlinko analyzing 11.8 million Google search results, pages with optimized alt text ranked on average 1.4 positions higher than pages without alt text. This small piece of code is truly a mighty tool for both accessibility and SEO performance.

Understanding Alt Text: The Key to Accessible and SEO-Optimized Images #

Defining Alt Text: What It Is and Its Purpose #

Alt text (alternative text) is a concise textual description added to image HTML tags that describes the appearance and function of an image on a webpage. Found in the “alt” attribute of the image tag, it’s a fundamental element that serves multiple critical purposes in web design and functionality.

At its core, alt text answers the question “what is alt text” by providing a text alternative when images can’t be seen. Whether the user has a visual impairment, is using a screen reader, or experiences technical issues with image loading, alt text ensures the information contained in the image remains accessible.

The purpose of alt text extends beyond simple descriptions—it communicates the essential meaning and context of visual elements. For instance, if an image shows a graph displaying quarterly sales increases, effective alt text wouldn’t just say “sales graph” but might specify “Bar graph showing 15% sales increase across all quarters of 2023.”

The Dual Role of Alt Text: Accessibility and SEO Benefits #

Alt text accessibility represents one of its primary functions. For users with visual impairments who rely on screen readers, these descriptions are the only way to understand image content. Without proper alt text, these users miss crucial information, creating barriers to equal access and potentially violating accessibility standards.

From an SEO perspective, does alt text help SEO? Absolutely. Search engines can’t “see” images the way humans do—they rely on alt text to understand what images contain. Research published in 2023 showed that websites prioritizing descriptive and relevant alt text experienced a 35% increase in organic traffic from image searches. Well-crafted alt text helps search engines index your images properly and understand their relevance to your content, improving your rankings for both traditional and image searches.

The optimization value is clear: images with descriptive alt text create additional opportunities to incorporate relevant keywords naturally. However, it’s critical to maintain a balance—alt text should primarily describe the image accurately while incorporating keywords only when they enhance understanding rather than stuffing them artificially.

Brief History and Evolution of Alt Text #

Alt text has been part of HTML since the early days of the web. When HTML 2.0 was published in 1995, it included the alt attribute as an optional element for image tags. However, with the creation of the Web Accessibility Initiative (WAI) by the W3C in 1997, alt text began to gain prominence as an accessibility tool.

The evolution of alt text paralleled the growing awareness of web accessibility. As the internet became increasingly visual, the importance of providing text alternatives for non-visual users became more apparent. The introduction of Section 508 compliance in the United States in 1998 and later the Web Content Accessibility Guidelines (WCAG) formalized the requirements for alt text.

In recent years, alt text has evolved beyond its original accessibility purpose to become an integral part of SEO strategy. Search engines like Google now use sophisticated image recognition technology in conjunction with alt text to better understand and index visual content. According to Reboot Online’s 2025 Website Statistics Report, the proportion of websites with missing alt-text fell by almost 10% between 2019-2023, indicating greater adoption of this SEO practice.

The Importance of Alt Text in Digital Content #

Enhancing User Experience: Why Screen Readers Rely on Alt Text #

Understanding why is alt text important begins with recognizing its role in accessibility. For users with visual impairments, screen readers serve as their eyes when navigating the web. These assistive technologies convert text-based content into synthesized speech—but they can’t interpret images without help.

Alt text bridges this critical gap by providing screen readers with descriptive text to convey what’s in an image. Without it, visually impaired users encounter frustrating gaps in content where images appear. Imagine reading an article where every few sentences, crucial information simply disappears—that’s the experience of encountering images without alt text.

“Alt text is the cornerstone of inclusive web design. When implemented properly, it ensures that users with screen readers don’t just know an image exists—they understand its content and context, making the difference between partial and complete access to information.” — Sheri Byrne-Haber, Accessibility Advocate and CPACC

The importance of alt text for images extends beyond just providing basic descriptions. Effective alt text conveys not just what an image shows, but its context and purpose within the content. For example, a product photo needs alt text describing key features, while an infographic requires alt text summarizing the data it presents.

Even for users without visual impairments, alt text enhances experience by providing context when images fail to load due to slow connections or technical errors. This creates a more robust, resilient user experience that works across varying technological capabilities.

SEO Influence: How Alt Text Impacts Search Rankings #

Is alt text important for SEO? Search engines emphatically answer “yes.” While search algorithms continue to advance in image recognition capabilities, they still rely heavily on textual cues to understand visual content. Alt text provides these critical context clues.

Google and other search engines use alt text to:

• Index image content properly
• Understand the relationship between images and surrounding text
• Determine relevance for both traditional and image search results
• Associate keywords with visual content for more accurate rankings

The importance of alt text becomes particularly evident in image search results, where properly optimized images can drive significant traffic. According to a 2024 analysis by JEMSU, websites with properly optimized alt text saw a 47% improvement in their image search rankings compared to those that neglected this aspect. Additionally, DirectOM’s 2024 update reports that websites prioritizing descriptive and relevant alt text have seen up to a 15% increase in click-through rates from image search results.

“While many SEO factors remain somewhat mysterious, the value of proper alt text is crystal clear. It’s one of the few direct ways to tell search engines exactly what your images represent, creating a powerful connection between visual content and search intent.” — Lily Ray, SEO Director at Path Interactive

Search engines also consider accessibility factors when ranking pages, so proper alt text implementation signals to algorithms that your site prioritizes quality user experience—potentially providing a ranking advantage over less accessible competitors.

Legal Implications: Accessibility Compliance and Potential Lawsuits #

The question “is image alt text important?” takes on additional significance when considering legal requirements. Web accessibility is increasingly recognized as a civil rights issue, with legal frameworks requiring digital content to be accessible to people with disabilities.

The Americans with Disabilities Act (ADA) has been interpreted by courts to apply to websites, even though it was written before the internet became ubiquitous. Organizations failing to implement accessibility features like alt text have faced lawsuits with significant financial consequences:

1. Target Corporation settled a landmark class action lawsuit for $6 million in 2008 over website accessibility issues, including lack of alt text for images. This case helped establish that websites can be considered “places of public accommodation” under the ADA.
2. Domino’s Pizza faced a lawsuit in 2019 over its website and mobile app not being fully accessible to screen reader users, with missing alt text specifically cited. The court ruled in favor of the plaintiff and ordered Domino’s to fix accessibility issues and pay $4,000 in damages.
3. Beyoncé’s company Parkwood Entertainment was sued in 2019 over accessibility issues on Beyonce.com, including lack of alt text for important images, among other WCAG violations.

The Web Content Accessibility Guidelines (WCAG), while not law themselves, are referenced in regulations worldwide. WCAG 2.1 explicitly requires text alternatives for all non-text content, making alt text a compliance necessity. In jurisdictions like the EU with the European Accessibility Act, Canada with the Accessibility for Ontarians with Disabilities Act, and many others, digital accessibility requirements explicitly include proper image descriptions.

Beyond avoiding litigation, implementing alt text demonstrates corporate social responsibility and ethical business practices. Organizations that prioritize accessibility often discover that inclusive design benefits all users while opening their products and services to the approximately 1 billion people worldwide living with disabilities—a substantial market segment often overlooked.

Optimizing Alt Text: Best Practices and Techniques #

General Guidelines: What Makes Good Alt Text #

Learning how to write alt text effectively requires understanding several core principles that balance accessibility needs with SEO considerations. At its foundation, good alt text should accurately represent an image’s content and purpose within its context.

To write good alt text, start by being concise yet descriptive. Most screen readers perform best with alt text under 125 characters, so prioritize clarity and focus on the most important elements of the image. Think about what information a user would miss if they couldn’t see the image—this is what your alt text should convey.

Alt text best practices emphasize context relevance. Rather than isolated descriptions, effective alt text connects images to their surrounding content. For example, a photo of a mountain on a general travel site might use “Snow-capped Mount Rainier against a clear blue sky,” while the same image on a climbing equipment page might use “Technical climber scaling Mount Rainier’s challenging northeast face.”

Keywords should appear naturally within alt text when relevant, but never at the expense of descriptive accuracy. Search engines have become increasingly sophisticated at detecting keyword stuffing in alt attributes, which can actually harm rather than help rankings.

Specific Scenarios: Alt Text for Complex and Decorative Images #

Functional Images and their Unique Requirements #

Functional images like buttons, icons, and linked images require special attention in their alt text. Image alt tag best practices for these elements focus on describing their function rather than appearance. For instance, a shopping cart icon used as a button should have alt text like “View shopping cart” rather than “Shopping cart icon.”

For images that serve as links, describe the destination rather than the image itself. If a company logo links to the homepage, appropriate alt text might be “Company Name – return to homepage” rather than “Company logo.” This approach helps screen reader users understand where clicking will take them.

Charts, graphs, and infographics present a particular challenge due to their information density. When applying alt text best practices to these complex images, provide a concise summary of the key data points or conclusions rather than attempting to describe every visual element. For example, “Graph showing steady increase in renewable energy adoption from 2010-2023, with solar growing 15% annually” communicates the essential information without overwhelming detail.

Handling Decorative Images and When to Omit Alt Text #

Contrary to common belief, not all images require descriptive alt text. Decorative images that don’t convey meaningful information should have empty alt attributes (alt=””) rather than being ignored altogether. This empty attribute signals to screen readers that the image is presentational and can be skipped, improving the user experience by reducing unnecessary interruptions.

Examples of decorative images include:

• Background textures and patterns
• Decorative borders and dividers
• Purely aesthetic photos that don’t add informational content
• Repeated icons used for visual appeal rather than functionality

The decision to use empty alt text should be made carefully. If an image contributes any meaningful content or context to the page, it deserves descriptive alt text. When in doubt, consider whether the absence of the image would diminish understanding of the surrounding content.

Crafting Effective Alt Text: Tips and Common Mistakes to Avoid #

One of the most common mistakes when learning how to write alt text is being either too vague or excessively detailed. Vague descriptions like “image” or “photo” provide no value, while overly lengthy descriptions can overwhelm screen reader users. Aim for the sweet spot that captures essential information without unnecessary details.

Image alt text best practices recommend avoiding redundancy. Don’t begin alt text with phrases like “image of” or “picture showing”—screen readers already announce the element as an image. Similarly, avoid repeating information that’s already present in nearby headings or paragraphs.

Here are additional tips to perfect your alt text:

• Use proper grammar and complete sentences when the length warrants it
• Prioritize front-loading important information, as some users may interrupt lengthy descriptions
• Include relevant emotions, actions, or atmosphere when they contribute to the image’s purpose
• Use specific language rather than vague descriptors (e.g., “golden retriever puppy” vs. “dog”)
• Test your alt text by closing your eyes and having someone read it—does it adequately replace the visual?

Avoid the trap of writing purely for SEO at the expense of clarity. While keywords have their place in alt text, their inclusion should feel natural and appropriate. Forced keyword placement creates awkward descriptions that serve neither accessibility nor search optimization goals effectively.

Visual Reference Table: Poor vs. Excellent Alt Text Examples #

Technical Implementation: How to Add Alt Text to Images #

Embedding Alt Text in HTML: A Step-by-Step Guide #

Adding alt text to images at the code level is straightforward once you understand the html alt attribute structure. The basic syntax follows this pattern:

<img src="image-file-name.jpg" alt="Descriptive text about the image">

When adding alt text directly in HTML, ensure you include the attribute for every image element. The process typically follows these steps:

1. Locate the <img> tag in your HTML document
2. Add the alt attribute after the src attribute
3. Write a concise, descriptive alternative text within quotation marks
4. Ensure your description accurately represents the image content

For images that are purely decorative, include an empty alt attribute (alt="") rather than omitting it entirely. This signals to screen readers that the image can be skipped without missing important content.

Here are examples of good alt text in HTML implementation:

<!-- Informative image example -->
<img src="golden-retriever-puppy.jpg" alt="Golden retriever puppy playing with a blue ball">

<!-- Functional image example (button) -->
<img src="search-icon.png" alt="Search">

<!-- Decorative image example -->
<img src="decorative-divider.png" alt="">

When working with complex images like charts or diagrams, you might need to use the longdesc attribute in addition to alt text, though modern accessibility practices often favor including detailed descriptions directly in the surrounding content.

Using Various Platforms: Adding Alt Text in Microsoft 365 and Other Tools #

The process for how to add alt tags to images varies across different platforms and content management systems. Most modern systems make adding alt text accessible through their user interfaces.

In Microsoft 365, the process for adding alt text is consistent across applications:

1. Right-click on the inserted image
2. Select “Edit Alt Text” (or “Alt Text” in some versions)
3. Enter your descriptive text in the panel that appears
4. Click “Close” to save

WordPress users can add alt text when uploading images to the Media Library or directly when inserting images into posts. Simply locate the “Alt Text” field in the attachment details and enter your description. Similar options exist in other popular CMS platforms like Shopify, Wix, and Squarespace.

Social media platforms have increasingly recognized the importance of alt text:

• Twitter allows adding alt text by enabling the feature in accessibility settings
• Instagram offers an “Add Alt Text” option in advanced settings when creating posts
• Facebook automatically generates alt text using AI but allows manual overrides

When creating content in Google Docs, right-click on an image and select “Alt text” to access the alt text panel. Similarly, in email marketing platforms like Mailchimp, look for alt text fields when adding images to your campaigns.

Alt text examples across these platforms should follow the same quality principles regardless of where they’re implemented—being concise, descriptive, and contextually relevant.

Evaluating and Testing Alt Text: Ensuring Effectiveness and Compliance #

Adding alt text is only the beginning; evaluating its effectiveness is equally important. Regular testing helps ensure your alt text serves its intended purpose for both accessibility and SEO.

To test how your alt text performs with screen readers:

1. Use built-in screen readers like VoiceOver (Mac), Narrator (Windows), or TalkBack (Android)
2. Navigate to pages containing your images
3. Listen to how the screen reader interprets your alt text
4. Note any awkward phrasing, redundancies, or unclear descriptions

Automated accessibility checkers can help identify missing alt text across your site. Tools like WAVE, axe, or Lighthouse scan pages and flag images without proper alt attributes. However, these tools can only verify the presence of alt text, not its quality.

For manual evaluation, review your alt text examples against these criteria:

• Does it accurately describe the image?
• Is it concise yet comprehensive?
• Does it avoid redundancy with surrounding content?
• Does it provide context relevant to the page topic?
• For functional images, does it describe the function rather than appearance?

Consider creating an internal style guide with alt text examples specific to your content needs. This helps maintain consistency, especially when multiple content creators work on the same site.

For compliance verification, familiarize yourself with WCAG (Web Content Accessibility Guidelines) requirements for alt text. WCAG 2.1 Success Criterion 1.1.1 (Non-text Content) provides the standard against which your alt text implementation will be measured for legal compliance.

Remember that effective alt text implementation is not a one-time task but an ongoing commitment to accessibility and user experience. Regular audits and updates ensure your alt text continues to serve all users effectively as your content evolves.

Troubleshooting: Common Alt Text Mistakes and How to Fix Them #

Problem: Missing Alt Text #

Issue: Images lack the alt attribute entirely, creating accessibility barriers. Solution: Implement a systematic audit of your website using tools like WAVE or axe to identify all images missing alt attributes. Prioritize high-traffic pages and progressively work through your site, adding appropriate descriptions for each image.

Problem: Generic or Uninformative Alt Text #

Issue: Alt text like “image,” “photo,” or “pic1” provides no value to users with visual impairments. Solution: Replace generic descriptions with specific content that describes what the image shows and its purpose on the page. For example, instead of “image,” use “Company CEO Jane Smith speaking at 2024 industry conference.”

Problem: Keyword Stuffing #

Issue: Overloading alt text with keywords creates an unnatural reading experience for screen reader users. Example: “Best affordable running shoes Nike discount running shoes sale cheap sneakers” Solution: Restructure alt text to prioritize clear description while naturally incorporating relevant keywords: “Nike Revolution 6 men’s running shoes in blue, side view showing cushioned sole.”

Problem: Redundant Information #

Issue: Alt text repeats information already available in captions or surrounding text. Solution: Review the content surrounding each image and craft alt text that complements rather than duplicates this information. If a detailed caption explains an image, the alt text can be more concise.

Problem: Over-Description of Decorative Images #

Issue: Providing detailed alt text for purely decorative images creates unnecessary interruptions for screen reader users. Solution: Use empty alt attributes (alt=””) for decorative images that don’t convey information or serve a functional purpose.

Problem: Insufficient Context for Complex Images #

Issue: Alt text for charts, graphs, or infographics fails to convey the essential information. Solution: Focus on summarizing the key takeaways rather than describing visual aspects. For example, for a climate change graph, emphasize the trend: “Graph showing 1.5°C global temperature increase from 1900-2023, with steepest rise occurring since 1980.”

Problem: Accessibility Audit Failures #

Issue: Automated accessibility tools flag your alt text as problematic despite having text present. Solution: Review specific failure reasons, which often include:

• Text exceeding recommended length (fix by being more concise)
• File names used as alt text (replace with proper descriptions)
• Non-descriptive placeholders (replace with meaningful content)
• Text not matching the image content (update for accuracy)

Advanced Insights and Resources #

Case Studies and Real-World Examples of Effective Alt Text #

Understanding what alt text is in practice often requires examining real-world implementations. Several organizations have demonstrated remarkable improvements in both accessibility and search performance through strategic alt text optimization.

Case Study 1: Ecommerce Site Transformation #

An online retailer specializing in outdoor equipment implemented a comprehensive alt text strategy across their 5,000+ product images. Before the implementation, their product images had generic alt text that primarily repeated the product name.

Before: <img src="hiking-boot.jpg" alt="hiking boot">After: <img src="hiking-boot.jpg" alt="Waterproof men's hiking boots with Gore-Tex lining and vibram sole for rocky terrain">

Results: Within six months, the site experienced a 21% increase in organic traffic according to a 2023 case study by Accessibly. Image search traffic specifically increased by 47%, and the average time spent on product pages improved by 15%. The accessibility score for the website improved from 72 to 94 out of 100.

Case Study 2: The British Museum’s Online Collection #

The British Museum’s online catalog features over 4 million objects, each with carefully crafted image descriptions. Their approach demonstrates exemplary alt text for cultural and historical content.

Before: <img src="artifact-1250BCE.jpg" alt="Ancient Egyptian artifact">After: <img src="artifact-1250BCE.jpg" alt="Limestone canopic jar with hieroglyphic inscriptions, depicting god Imsety, 1250 BCE">

This level of specificity follows alt text best practices by providing context, time period, and material information relevant to researchers and visitors alike. The museum reported a 32% increase in image discovery through search engines after implementing these changes.

Case Study 3: Weather Information Platform #

The Weather Channel’s website illustrates expert handling of complex informational graphics. Their radar images include alt text that communicates essential weather information.

Before: <img src="radar-map.jpg" alt="Radar map">After: <img src="radar-map.jpg" alt="Doppler radar showing severe thunderstorms moving northeast across central Oklahoma, with potential tornado formation in red zones">

This approach prioritizes conveying critical information rather than describing visual elements. After implementing these changes, the site saw user engagement increase by 18% among screen reader users and reported higher satisfaction ratings in accessibility surveys.

“High-quality alt text isn’t just about meeting a technical requirement—it’s about providing equal access to information. When we improved our alt text quality across our scientific publications, we saw engagement from visually impaired users increase by over 200%.” — Dr. Amal Sharma, Digital Accessibility Director, Scientific American

Evolving Trends: The Future of Alt Text in AI and Machine Learning #

The landscape of alt text implementation is rapidly evolving as artificial intelligence and machine learning technologies advance. While automated alt text generation has existed for years, early versions produced generalized descriptions like “image may contain: people, outdoors.” Today’s AI systems are becoming remarkably more sophisticated.

A 2023 study found that human experts produced acceptable descriptions for all test images, while AI struggled more with complex images like illustrations and charts. Human-written alt text averaged a quality rating of 3.8 (experts) and 3.0 (novices) out of 5, while AI-generated text averaged only 1.9. Even the best AI tools rarely scored as “acceptable” (3 or higher out of 5) in quality ratings.

Microsoft’s Azure Cognitive Services and Google’s Cloud Vision API now generate increasingly accurate image descriptions, though they still struggle with nuance and context. These tools are best used as starting points that human editors refine rather than as complete solutions. Current image alt text best practices still emphasize human review of AI-generated descriptions to ensure accuracy and relevance.

An emerging trend is context-aware alt text generation, where AI considers not just the image itself but surrounding content, page purpose, and user journey. Facebook’s automatic alt text system now includes object relationships and activities, generating descriptions like “Three people smiling at an outdoor restaurant with mountains in background” instead of simply listing detected elements.

New AI tools focused specifically on alt text generation have emerged, such as AltText.ai, a dedicated tool for generating alt text that has received positive reviews for its accuracy and integration with platforms like WordPress. Another example is FigurA11y, an interactive system designed to help authors write alt text for scientific figures by combining AI suggestions with human input.

Despite these advances, human judgment remains irreplaceable for determining appropriate alt text length and detail based on image context and purpose. Even as AI improves, understanding the communicative goal of an image within content is still a uniquely human skill.

Additional Resources for Further Learning and Implementation #

For professionals looking to deepen their understanding of alt text best practices, several authoritative resources provide comprehensive guidance:

The Web Accessibility Initiative (WAI) offers an extensive guide on “Alternative Text for Images” that breaks down decision trees for different image types. Their resources include interactive tutorials demonstrating how screen readers interpret various alt text approaches in real-time.

WebAIM’s “Alternative Text” guide provides practical examples of good alt text across different contexts, from decorative images to complex data visualizations. Their before-and-after examples illustrate common pitfalls and effective solutions.

For those seeking hands-on tools, the WAVE Web Accessibility Evaluation Tool by WebAIM highlights missing or problematic alt text on any webpage, providing immediate feedback for improvement. Similarly, the Accessibility Insights browser extension offers guided assessments of alt text implementation.

Several online courses specifically address image alt text within broader accessibility training:

• Deque University’s “Web Accessibility” curriculum includes dedicated modules on writing effective alt text
• Google’s Digital Garage offers a free “Make your website more accessible” course with sections on image descriptions
• The A11Y Project provides community-reviewed resources for implementing accessible alt text patterns

Organizations developing accessibility policies should reference the WCAG 2.1 Guidelines, particularly Success Criterion 1.1.1 on non-text content, which provides the technical standards against which alt text is evaluated for compliance.

For content creators seeking practical reference materials, Moz’s “Alt Text as an SEO Factor” guide merges accessibility best practices with search optimization techniques, offering a balanced approach to serving both purposes effectively.

By utilizing these resources and staying current with evolving standards, content creators and developers can ensure their alt text implementation remains both accessible and optimized for discovery—serving the widest possible audience regardless of ability or technology.