Images play a crucial role in modern websites, but search engines and screen readers cannot fully understand visual content without proper descriptions. This is where alt text becomes essential. Writing effective alt text improves website accessibility, enhances user experience, and can contribute to better SEO performance.
In this guide, you’ll learn what alt text is, why it matters, and how to write alt text for images correctly.
What Is Alt Text?
Alt text, short for alternative text, is a written description added to an image’s HTML code. It serves as a replacement when an image cannot be displayed and helps screen readers explain image content to visually impaired users.
For example:
- Poor Alt Text: “image123.jpg”
- Good Alt Text: “Golden retriever puppy playing with a red ball in a garden”
The second example provides meaningful context that both users and search engines can understand.
Why Alt Text Is Important
Improves Website Accessibility
Alt text allows screen readers to describe images to users who cannot see them. Accessibility is a fundamental aspect of web design and helps ensure equal access to information.
Enhances SEO Performance
Search engines use alt text to understand image content. Well-written descriptions can help images appear in image search results and provide additional context for page relevance.
Provides Context When Images Fail to Load
If an image cannot load because of a technical issue or slow internet connection, alt text appears in its place, helping users understand what the image was intended to show.
Supports Better User Experience
Clear image descriptions improve content comprehension and help visitors navigate information more effectively.
How to Write Alt Text for Images
Describe the Image Accurately
Focus on what is actually shown in the image. Provide enough detail for someone who cannot see the image to understand its purpose.
Example:
- Bad: “Dog”
- Better: “Brown Labrador retriever running on a beach at sunset”
Keep It Concise
Most effective alt text descriptions are between 5 and 15 words. Include relevant details without creating lengthy sentences.
Example:
- Too Long: “A beautiful and energetic brown Labrador retriever that appears to be running very quickly across a sandy beach during a colorful sunset.”
- Better: “Brown Labrador retriever running on a beach at sunset”
Include Relevant Keywords Naturally
If the image relates to your target keyword, include it naturally within the description. Avoid forcing keywords where they do not fit.
Example:
For a blog about home office design:
- Good Alt Text: “Modern home office setup with ergonomic chair and dual monitors”
Avoid Keyword Stuffing
Stuffing keywords into alt text can harm user experience and may be viewed as spam.
Example:
- Bad: “Home office design, home office ideas, home office furniture, home office setup”
- Good: “Modern home office with wooden desk and ergonomic chair”
Do Not Start With “Image Of” or “Picture Of”
Screen readers already announce that an element is an image. Adding phrases like “image of” creates unnecessary repetition.
Example:
- Bad: “Image of a mountain landscape”
- Good: “Snow-covered mountain landscape during sunrise”
Consider the Context
The same image may require different alt text depending on the page’s content and purpose.
For example, an image of a laptop could be described as:
- “Business professional working on a laptop”
- “Lightweight laptop with 14-inch display”
- “Remote employee attending a virtual meeting”
Choose the description that best matches the page topic.
Alt Text Examples for Different Image Types
Product Images
Example:
“Black leather backpack with multiple storage compartments”
Blog Images
Example:
“Content marketer analyzing website traffic reports”
Infographics
Example:
“Infographic showing five stages of the customer journey”
Team Photos
Example:
“Customer support team members working together in an office”
Charts and Graphs
Example:
“Line chart showing website traffic growth from January to June”
Common Alt Text Mistakes to Avoid
Using File Names
Avoid descriptions like:
- DSC001.jpg
- IMG_2025.png
These provide no useful information.
Writing Vague Descriptions
Examples such as “photo” or “graphic” fail to communicate the image’s meaning.
Ignoring Decorative Images
Purely decorative images that add no informational value should often use empty alt attributes.
Example:
alt=””
This tells screen readers to skip unnecessary content.
Overloading With Keywords
Always prioritize clarity and user understanding over search engine optimization.
Alt Text Best Practices Checklist
Before publishing an image, ask yourself:
- Does the alt text accurately describe the image?
- Is it concise and easy to understand?
- Does it provide value to screen reader users?
- Is the description relevant to the page content?
- Have unnecessary words been removed?
- Are keywords included naturally rather than forced?
How Alt Text Impacts SEO
While alt text alone will not guarantee higher rankings, it supports overall SEO efforts by:
- Helping search engines understand image content.
- Improving image search visibility.
- Strengthening page relevance signals.
- Enhancing accessibility and user experience.
- Supporting compliance with accessibility standards.
A website that combines high-quality content, optimized images, and descriptive alt text creates a stronger foundation for long-term search performance.
Frequently Asked Questions
How Long Should Alt Text Be?
Most alt text should be concise, typically under 125 characters, while still providing meaningful context.
Should Every Image Have Alt Text?
Most images should have alt text. Decorative images can use empty alt attributes so screen readers ignore them.
Can Alt Text Improve Google Rankings?
Alt text helps search engines understand image content and may improve image search visibility, contributing to overall SEO performance.
Should Keywords Be Included in Alt Text?
Yes, but only when they naturally fit the image description and page context.
Conclusion
Learning how to write alt text for images is an essential skill for website owners, content creators, and SEO professionals. Effective alt text improves accessibility, enhances user experience, and helps search engines better understand visual content.
The best alt text is accurate, concise, contextually relevant, and written primarily for users rather than search engines. By following these best practices, you can create a more accessible website while strengthening your overall SEO strategy.