Images make content more engaging—but search engines and visually impaired users can’t “see” them the way humans do. That’s where alt text comes in.
If done right, alt text improves SEO performance, accessibility, and user experience. If done poorly, it can hurt both rankings and usability.
In this guide, you’ll learn exactly how to write effective alt text that works for both Google and real people.
What Is Alt Text?
Alt text (alternative text) is a short written description of an image added in HTML. It serves two main purposes:
- Helps search engines understand what an image is about
- Assists screen readers for visually impaired users
When an image fails to load, alt text is also displayed instead.
Example:
<img src="seo-guide.jpg" alt="SEO checklist for beginners on a laptop screen">
Why Alt Text Matters for SEO
Alt text plays a key role in image SEO optimization and overall page relevance.
Here’s why it matters:
- Helps Google index your images properly
- Improves chances of ranking in Google Images
- Strengthens page relevance for target keywords
- Enhances accessibility compliance (WCAG standards)
- Improves user experience when images fail to load
In short, alt text connects your visuals with search engines and users at the same time.
Alt Text Best Practices (Simple but Powerful Rules)
1. Be Descriptive but Concise
Good alt text clearly explains what’s in the image without being too long.
✔ Good:
- “Digital marketing team analyzing SEO performance on a dashboard”
✖ Bad:
- “Image of people working in an office doing marketing SEO strategy analytics data computer screen graph chart performance optimization”
Keep it natural and readable.
2. Use Keywords Naturally (Don’t Stuff Them)
Yes, keywords help—but only when they fit naturally.
✔ Good:
- “SEO keyword research process shown on laptop screen”
✖ Bad:
- “SEO keyword SEO optimization SEO tools SEO ranking SEO strategy image”
Search engines are smarter than keyword stuffing.
3. Describe the Function, Not Just the Appearance
If an image has a purpose, explain it.
Examples:
- A button → “Search button to submit query”
- A chart → “Traffic growth chart showing increase over 6 months”
- A product → “Black wireless headphones with noise cancellation”
This improves usability and accessibility.
4. Skip “Image of” or “Picture of”
Screen readers already know it’s an image.
✖ Avoid:
- “Image of SEO strategy diagram”
✔ Better:
- “SEO strategy diagram showing content, backlinks, and technical SEO”
5. Keep It Short (Usually Under 125 Characters)
Most screen readers cut off long alt text.
Aim for:
- Clear
- Direct
- Informative
6. Don’t Use Alt Text for Decorative Images
If an image is purely decorative (like background shapes or spacing), use empty alt text:
alt=""
This helps screen readers skip unnecessary content.
7. Match Context of the Page
Alt text should reflect how the image is used in the content.
For example:
- On a blog about SEO tools → “Ahrefs dashboard showing keyword difficulty and traffic data”
- On a blog about blogging → “Content writer drafting a blog post with SEO outline”
Context matters as much as description.
8. Be Specific, Not Generic
Avoid vague descriptions.
✖ Bad:
- “Chart”
- “Laptop”
- “Team meeting”
✔ Good:
- “Line chart showing organic traffic growth over 12 months”
- “Laptop displaying Google Analytics SEO report”
- “Marketing team discussing content strategy in office”
Common Alt Text Mistakes to Avoid
- Keyword stuffing
- Writing overly long sentences
- Leaving important images without alt text
- Using irrelevant keywords
- Repeating the same alt text across images
These mistakes can hurt both SEO and accessibility.
Simple Alt Text Examples
| Image Type | Good Alt Text |
|---|---|
| Blog banner | “SEO optimization guide for improving website rankings” |
| Product image | “White running shoes with breathable mesh design” |
| Chart | “Bar chart showing monthly website traffic growth” |
| Infographic | “Steps of on-page SEO optimization process” |
FAQ: Alt Text Best Practices
What is the ideal length for alt text?
Usually under 125 characters is best—short, clear, and descriptive.
Does alt text help SEO rankings?
Yes. It improves image search visibility and helps Google understand page context.
Should every image have alt text?
Most images should. Decorative images can use empty alt attributes.
Can I use keywords in alt text?
Yes, but only when they naturally fit the description. Avoid stuffing.
What’s the difference between alt text and captions?
Alt text is for search engines and screen readers. Captions are visible to all users.
Conclusion
Writing effective alt text is not complicated—but it requires intention. The goal is simple: describe your image in a way that helps both users and search engines understand it clearly.
When done right, alt text improves:
- SEO performance
- Accessibility compliance
- User experience
- Content relevance
Small detail, big impact.
