Images are an essential part of web content, enhancing user experience, visual appeal, and engagement. However, not all users can see images. Some may have visual impairments, slow internet connections, or use text-based browsers. This is where the alt (alternative text) attribute comes into play.
The alt attribute provides a text description of an image, ensuring that users who cannot see the image still understand its purpose. But its importance goes beyond accessibility—it also plays a role in SEO (Search Engine Optimization) and user experience.
In this article, we’ll explore the purpose, best practices, and impact of alt attributes, along with practical examples and SEO insights.
What is the alt Attribute?
The alt attribute is an HTML attribute used in the <img> tag to provide alternative text for an image. It is displayed if the image fails to load and is read aloud by screen readers for visually impaired users.
Example:
<img src="sunset.jpg" alt="Beautiful orange and purple sunset over the ocean">
If the image does not load, users will see:
“Beautiful orange and purple sunset over the ocean” instead of a broken image icon.
Why is the alt Attribute Important?
1. Accessibility (A11y)
- Helps visually impaired users: Screen readers read the
alttext aloud, allowing users to understand what the image represents. - Required for compliance: Web accessibility standards like WCAG (Web Content Accessibility Guidelines) mandate meaningful
alttext for non-decorative images.
2. SEO (Search Engine Optimization)
- Improves image search rankings: Search engines like Google use
alttext to understand and index images. - Increases organic traffic: Well-written
alttext can help your images appear in Google Image Search, driving more visitors to your website.
3. Improved User Experience
- Provides context when images fail to load: Users with slow internet connections or broken image links can still understand the image’s purpose.
Best Practices for Writing alt Text
✅ 1. Be Descriptive but Concise
- Good Example:
<img src="dog.jpg" alt="Golden retriever playing in a park"> - Bad Example:
<img src="dog.jpg" alt="Dog">
Why? The first example provides useful context, while the second is too vague.
✅ 2. Avoid “Image of” or “Picture of”
- ❌ Bad:
<img src="tree.jpg" alt="Image of a tree"> - ✅ Good:
<img src="tree.jpg" alt="Large oak tree with autumn leaves">
Why? Screen readers already indicate it’s an image, so “Image of” is unnecessary.
✅ 3. Use Empty alt for Decorative Images
If an image is purely decorative and does not add meaning to the content, leave the alt attribute empty.
<img src="border.jpg" alt="">
Why? This tells screen readers to ignore the image, preventing unnecessary distractions.
✅ 4. Include Keywords (Without Keyword Stuffing)
- Good Example:
<img src="blue-running-shoes.jpg" alt="Men's blue running shoes with white soles"> - Bad Example (Keyword Stuffing):
<img src="blue-running-shoes.jpg" alt="Blue running shoes, best running shoes, buy running shoes online">
Why? The first example is natural and helpful, while the second is spammy and may hurt SEO.
✅ 5. Use Proper Punctuation for Better Accessibility
Screen readers pause at punctuation marks, making descriptions easier to understand.
- Example:
<img src="forest.jpg" alt="Dense green forest. Sunlight filtering through tall trees.">
Why? The period helps screen readers pause, improving clarity.
Common Mistakes to Avoid
❌ Missing alt attributes on meaningful images
- Bad:
<img src="chart.png"> - Good:
<img src="chart.png" alt="Bar chart showing monthly sales growth">
❌ Overly long alt descriptions
- Keep descriptions under 125 characters (most screen readers cut off after this).
❌ Using alt text for every image, even when unnecessary
- Leave decorative images blank (
alt="") to avoid cluttering screen reader output.
How alt Text Helps SEO
Google and other search engines use alt attributes to index images and understand their content. Properly written alt text can help your images rank in Google Image Search, driving traffic to your website.
SEO Best Practices:
✔ Include relevant keywords naturally
✔ Be specific and descriptive
✔ Avoid keyword stuffing
✔ Optimize file names (blue-running-shoes.jpg instead of image123.jpg)
Example of Optimized HTML for SEO:
<img src="nike-air-max-2023.jpg" alt="Nike Air Max 2023 sneakers in red and black color">
Conclusion
The alt attribute is crucial for accessibility, SEO, and user experience. By writing clear, concise, and meaningful alt text, you make your website more inclusive and improve your search rankings.
Key Takeaways:
✅ Use descriptive but concise alt text
✅ Leave alt empty for decorative images
✅ Avoid redundant words like “image of”
✅ Optimize for SEO naturally
✅ Use punctuation for better screen reader experience
📢 Call to Action
Have you optimized your website’s images with alt attributes? Try testing your site with a screen reader or an SEO tool and share your experience in the comments!