How Do Alt Tags Contribute to SEO for Images?


Alt tags, also known as alternative text, are HTML attributes used in image tags to describe the content of the images. They play a critical role in SEO by improving accessibility, providing context to search engines, and enhancing user experience. Implementing effective alt tags can contribute to higher search engine rankings and better discoverability of your images.

Accessibility Enhancement

Assistive Technologies

Alt tags are essential for accessibility because they are read aloud by screen readers used by visually impaired users. This provides a textual description of the image, allowing these users to understand the content and context better.

For example, an alt tag for an image of a golden retriever could be: <img src="golden-retriever.jpg" alt="Golden retriever playing in the park"> which would be read aloud to the user.

SEO Benefits

Image Indexing

Search engines like Google use alt tags to understand the content of images. This helps in indexing images properly, making them discoverable in image searches. An accurate and descriptive alt tag increases the likelihood of your image appearing in search results.

For instance, an image with an alt tag like <img src="pie-chart.gif" alt="Annual financial report showing revenue growth in 2022"> is more likely to be indexed for relevant searches.

Improved Relevance

Using relevant keywords in the alt tags can improve the page's relevance to search queries. However, it’s crucial to avoid keyword stuffing, as this can be penalized by search engines. Always aim for descriptive, concise, and relevant alt text.

User Experience

Fallback Content

If an image fails to load due to network issues or other problems, the alt tag provides a text description that ensures the user still gets the intended message. This contributes to a better user experience, particularly in environments with unreliable internet connections.

Specific Examples

Example 1: E-commerce Site

For a product image on an e-commerce site, a suitable alt tag could be <img src="red-dress.jpg" alt="Red evening dress with lace sleeves">. This helps search engines understand what the image is about and also enhances the user’s shopping experience.

Example 2: Blog Post

For an image in a blog post about travel, an appropriate alt tag might be <img src="paris-eiffel-tower.jpg" alt="Sightseeing at the Eiffel Tower in Paris during sunset">. This allows the image to be found in related searches and provides context to users.

Best Practices

Be Descriptive

Describe the image in a concise yet detailed manner. Aim to convey the same information that the image does.

Avoid Keyword Stuffing

Use keywords naturally and contextually within the alt tag. Stuffing keywords can lead to penalties from search engines.

Keep it Short

Alt tags should be concise, ideally under 125 characters, to ensure compatibility with screen readers and to provide clear, immediate information.


Incorporating well-crafted alt tags is a vital aspect of SEO for images. By enhancing accessibility, facilitating better image indexing, and improving user experience, effective alt tags can significantly boost your site's search engine performance.