What Is Alt Text? How To Craft Effective Alt Text for SEO

Alt text ensures that people using screen readers can understand the content of your images, making your website accessible to users with visual impairments. 

At the same time, search engines use alt text to index digital content, improving your SEO and helping your site rank in image search results. From product pages to graphical illustrations, knowing how to write effective alt text can enhance both user experience and online visibility. 

In this guide, we’ll cover what alt text is, why it matters, and actionable strategies to craft alt text that aligns with both accessibility standards and SEO best practices.

What Is Alt Text?

Alt text, short for alternative text, is a written description of an image that is embedded in the HTML code using the alt attribute. It serves as a textual alternative to visual content, ensuring that users who cannot see an image, for reasons like visual impairments, slow internet connections, or browser limitations, can still understand its content.

Alt text is used not only by screen readers but also by search engines, which rely on it to understand and index images. When done properly, it improves web accessibility and helps your images appear in image search results, enhancing your overall Search Engine Optimization (SEO).

Other Names for Alt Text

Alt text is also known as:

• Alternative text
• Alt attribute
• Image description
• Text alternative

These terms are often used interchangeably in web accessibility guidelines and SEO documentation.

Example of Alt Text in HTML

<img src=”central-park-skyline.jpg” alt=”Aerial view of Central Park surrounded by skyscrapers in New York City during autumn”>

This alt text provides a factual description, helping both users with disabilities and search engines understand the visual content.

Why Alt Text Matters

Alt text is critical for both accessibility and SEO. Here’s why:

1. Accessibility for Users with Disabilities

Approximately 2.2 billion people worldwide have some form of vision impairment. For these users, screen readers like JAWS Inspect or VoiceOver rely on alt text to interpret images. Without alt text, crucial information is inaccessible, violating Section 508 guidelines and the Web Content Accessibility Guidelines (WCAG).

2. SEO Benefits

Search engines cannot “see” images the way humans do. Alt text provides context that allows images to appear in image search results, boosting organic traffic. Well-crafted alt text also improves on-page SEO, contributing to higher rankings for digital content pages.

3. Better User Experience

Alt text can describe functional images like buttons or navigation icons, ensuring that all users, including those relying on assistive technologies, can navigate your website effectively. This aligns with modern UI design principles and improves web accessibility.

How to Add Alt Text

Adding alt text (alternative text) is a fundamental step in making your website both SEO-friendly and accessible. It involves inserting a descriptive phrase into the alt attribute within the HTML image tag, allowing screen readers, assistive technologies, and search engines to interpret your visual content accurately.

Whether you’re managing a blog, an eCommerce store, or a corporate website, understanding how to properly add alt text ensures your digital content is inclusive, optimized, and aligned with Web Content Accessibility Guidelines (WCAG).

1. Adding Alt Text in HTML Code

The most direct way to add alt text is through HTML code. Every image element should include an alt attribute, even if it’s empty for decorative purposes.

<img src=”central-park-autumn.jpg” alt=”Aerial view of Central Park with orange and yellow trees during fall in New York City”>

Key Elements:

• <img> = HTML image tag
• src = image source (file path)
• alt = text alternative describing the image

Why It Matters:

• Helps search engine spiders understand your image
• Improves image SEO and visibility in image search
• Ensures accessibility for users with visual impairments

Bad vs Good Example:

• Wrong: alt=”park”
• Correct: alt=”Aerial view of Central Park surrounded by skyscrapers in autumn”

The second example provides context, location, and visual details, making it more valuable for both users and search engines.

2. Adding Alt Text in Content Management Systems (CMS)

If you’re not working directly with code, most content management systems (CMS) like WordPress, Shopify, or Wix allow you to add alt text easily.

Steps:

1. Upload or select an image
2. Locate the “Alt Text” or “Image Description” field
3. Enter a concise, keyword-relevant description

Example for Different Use Cases:

E-commerce Product Page:

• Wrong: “jacket”
• Correct: “Women’s black leather jacket with zipper pockets and slim fit design”

Blog Image:

• Wrong: “marketing chart”
• Correct: “Line graph showing increase in organic traffic after SEO optimization”

Pro Tip:

Use tools like Yoast SEO or an SEO Checker tool to ensure your alt text for images aligns with your keyword strategy without keyword stuffing.

3. Adding Alt Text in Microsoft Products & Documents

Alt text is essential beyond websites; it’s also required in documents for accessible communications.

Microsoft Word, PowerPoint, Excel:

• Right-click on the image
• Select “Edit Alt Text.”
• Add a clear description in the panel

Example:

• Wrong: “chart”
• Right: “Bar chart comparing sales growth from 2022 to 2025 across three regions”

Adobe Acrobat (PDFs):

Use accessibility tools to add image descriptions to images in PDFs. This ensures compliance with Section 508 guidelines and supports students with disabilities or users relying on assistive technologies.

4. Handling Decorative vs Functional Images

Not all images require descriptive alt text. It’s important to distinguish between decorative images and functional images.

Decorative Images

These are purely visual and don’t add informational value (e.g., background patterns, design elements).

<img src=”background-texture.png” alt=””>

• Use an empty alt attribute (alt=””)
• Prevents screen readers from reading unnecessary content
• Improves overall user experience

Functional Images

These serve a purpose (buttons, icons, links).

<img src=”search-icon.png” alt=”Search button”>

• Describe the function, not the appearance
• Helps users navigate your web design effectively

5. Writing Alt Text for Complex Images

Some images, like charts, graphs, infographics, or maps, contain detailed visual information that cannot be summarized in one sentence.

Example:

<img src=”traffic-growth-chart.png” alt=”Graph showing website traffic growth increasing from 10,000 to 50,000 monthly visitors between January and June”>

Best Practice:

• Provide a short alt text summary
• Add a long description in surrounding content or link to a detailed explanation

This ensures compliance with accessibility requirements and improves comprehension for users relying on screen readers.

6. Optimizing Alt Text for SEO

To maximize Search Engine Optimization (SEO) benefits:

• Include relevant keywords naturally
• Match alt text with content context
• Use descriptive image filenames (e.g., red-running-shoes.jpg instead of IMG_1234.jpg).
• Combine alt text with image captions and schema markup

Example:

Not right: alt=”SEO, marketing, SEO services, best SEO agency” (keyword stuffing)

This is correct: alt=”SEO expert analyzing website traffic data on a dashboard”

7. Common Mistakes to Avoid

• Writing overly long descriptions
• Ignoring alt text completely
• Using generic phrases like “image” or “photo”
• Stuffing keywords unnaturally
• Forgetting alt text for product pages and important visuals

Quick Checklist for Adding Alt Text

Before publishing any image, ask:

✔ Does this image need alt text or is it decorative?
✔ Is the description clear and concise?
✔ Does it provide value to users with visual impairments?
✔ Is it aligned with the page’s SEO strategy?
✔ Does it follow accessibility guidelines like WCAG?

By implementing alt text correctly across your website, documents, and digital platforms, you create a more inclusive experience while strengthening your SEO performance. It’s a small step with a powerful impact on both accessibility and search engine visibility.

Alt Text Best Practices

Writing effective alt text requires a balance between accessibility and SEO. Follow these guidelines:

1. Be Descriptive but Concise.
   Use clear, factual descriptions. For example: “Aerial view of Central Park in autumn” rather than “Park view.”
2. Use Keywords Naturally
   Integrate target keywords relevant to your SEO strategy, but avoid keyword stuffing.
3. Avoid Redundant Phrases
   Phrases like “image of” or “picture of” are unnecessary because screen readers already announce it as an image.
4. Differentiate Functional vs. Decorative Images
   • Functional images (buttons, icons) need clear, action-oriented alt text.
   • Decorative images can use empty alt attributes (alt=””) to prevent screen readers from reading them unnecessarily.
5. Provide Long Descriptions for Complex Images
   For graphs, charts, or maps, include a long description explaining the data. Use separate sections or links if needed.
6. Follow Accessibility Guidelines
   Adhere to WCAG, Section 508, and recommendations from sources like Harvard University Digital Accessibility Resources, TPGi, or A11y Collective.

3 Alt Text Examples

Example 1: Product Image

• Image: Red running sneakers
• Alt Text: “Red running sneakers with white soles and breathable mesh upper for men”

Example 2: Infographic

• Image: Social media statistics chart
• Alt Text: “Bar chart showing 2026 social media usage: 60% mobile, 25% desktop, 15% tablet”

Example 3: Decorative Image

• Image: Background photo of clouds
• Alt Text: “” (empty, decorative)

Other Considerations

• Auto-Generated Alt Text: Tools like AI alt text generators provide suggestions, but always review for accuracy and context.
• SEO Integration: Use alt text alongside image filenames, title attributes, and captions for complete image SEO.
• Responsive Layout: Ensure alt text remains meaningful on mobile, desktop, and SVG images in responsive web design.

Conclusion

Alt text is an essential component of digital accessibility, user experience, and SEO. By providing clear, descriptive, and concise text alternatives, you make your visual content accessible to people with disabilities and understandable to search engines. From product images to complex graphs, every image on your website offers an opportunity to improve both accessibility and online visibility. 

For businesses in the USA and beyond, mastering alt text is a simple yet powerful way to ensure that your digital content reaches a wider audience while remaining compliant with accessibility standards. Start optimizing your images today and watch your website become more inclusive, discoverable, and engaging.

FAQs

1. What is alt text and why is it important?

Alt text, or alternative text, is a written description of an image embedded in the HTML code using the alt attribute. It helps screen readers describe images to users with visual impairments, ensures compliance with accessibility guidelines, and boosts SEO by helping search engines index visual content. Proper alt text enhances user experience, digital accessibility, and image search visibility.

2. How do I write effective alt text for SEO?

Effective alt text should be concise, descriptive, and keyword-relevant. Include factual descriptions of the image, avoid keyword stuffing, and distinguish between functional images and decorative images. For complex images, provide a long description or link to additional details. Always follow WCAG and Section 508 standards to ensure accessibility for all users.

3. Can decorative images have alt text?

Decorative images, such as background photos or visual borders, do not need descriptive alt text. Using an empty alt attribute (alt=””) ensures that screen readers skip these images, reducing unnecessary distractions while maintaining accessible communications for people with disabilities.

4. How does alt text impact SEO and website rankings?

Search engines rely on alt attributes to understand visual content. Properly optimized alt text improves image SEO, allowing images to appear in image search results, increasing organic traffic. Alt text also supports overall SEO by providing context for digital content, helping search engines interpret the topic and relevance of your pages more accurately.