The text description of the image on the website, used to describe the image Cannot see their users.
Alt tags (also known as “alt attributes” and “alt descriptions”) are HTML attributes applied to image tags to provide alternative text for search engines. Applying images to alt tags such as product photos can have a positive impact on the search engine ranking of e-commerce stores.
What does the alt tag do? Search engines and other robots cannot interpret images, but images can play a key role in people’s interpretation of specific web pages. Alt tags solve this problem by providing text read by search engines. When Googlebot or other search engine crawlers check the page, images with properly formatted alternative text will help the page build index and rank on the page.
Alt Text and SEO Benefits
Take a concrete case: an e-commerce business uploads 6,000 product images to its website. With descriptive alternative text on each image, visually impaired users can clearly understand every product through screen readers. This simple addition turns images from silent page elements into useful content, ensuring better access for all visitors. Over time, this can widen the business’s reach to more potential customers—an inclusivity step that also aligns with best practice for digital compliance.
On the SEO front, search engines cannot “see” images in the way humans do. Well-crafted alt text provides the necessary information, allowing search engines to read and index these images accurately. When images include relevant keywords and context, they can appear in image search results, driving more organic traffic. For a business with 6,000 images, this means a significant increase in visibility and potentially higher sales—especially if competitors ignore this detail.
- Write concise but clear alt text describing image content
- Include relevant keywords where they fit naturally
- Avoid keyword stuffing or irrelevant phrases
- Make each alt text unique for every image
- Test accessibility using a screen reader
- Update alt text as products or images change
How Search Engines Interpret Alt Text
Look at the numbers: A local hospitality business’s website sees 7,200 monthly sessions. If half its most valuable images are properly described with alt text, search engines can draw much clearer meaning from these visuals. This clarity improves the odds that pages featuring these images will rank for relevant search queries, as the search engine can now index these assets as part of the broader page context. Without well-crafted alternative text, those opportunities for visibility may be missed entirely.
Search engines don’t “see” images the way humans do. Instead, algorithms rely on the accompanying alternative text to interpret the image’s subject and context. Well-written alt text bridges that gap, making your images not just accessible to all users but also visible to crawlers as meaningful content. When images contribute context or substance, alt text supports them in influencing organic rankings, especially for image search.
- Use descriptive phrases, not just keywords, for alt text
- Avoid leaving alt text blank unless images are decorative
- Ensure each image gets unique, relevant alternative text
- Don’t stuff alt text with keywords; keep it natural
- Check alt text for typos and wording errors
- Review frequently to align with evolving SEO priorities
Common Mistakes in Writing Alt Text
Neglecting alt text quality is a frequent issue that affects both accessibility and search rankings. Many businesses either skip alt text altogether or write descriptions that fail to inform users, focusing instead on squeezing in keywords. Vague descriptions like “photo” or “banner” don’t provide useful information to people using screen readers. Overusing keywords in alt text, aiming to manipulate SEO, can also make content less accessible and could trigger search engine penalties.
In another common situation, marketers reusing the same alt text for every image on a website with 8,400 monthly sessions risk making the user experience frustrating for visually impaired visitors. Screen readers repeat the same non-descriptive phrases, so users lose context and clarity. When alt text is inaccurate or incomplete, visitors may not understand the purpose of essential images. This lack of clarity often results in increased bounce rates and reduced site engagement.
- Keyword stuffing, making alt text hard to read or spammy
- Writing overly generic phrases that add no value
- Omitting alt text from images completely
- Overusing identical alt text for multiple images
- Failing to describe the function of links or buttons properly
- Including information not visible in the image itself
- Using file names or code instead of a real description
Best Practices for Optimising Alt Text
Run the maths on this: suppose an average UK e-commerce site features 9,600 product images each month. If each image has clear, descriptive alt text, this can materially enhance both site accessibility for users with visual impairments and SEO visibility for organic search. However, vague or generic alt text—such as “image123” or simply “product”—misses both benefits, making it harder for assistive technology to convey meaning and for search engines to index the content effectively.
Common pitfalls include overstuffing alt text with keywords, making it difficult to read by screen readers, or creating alt text that is so lengthy it becomes unwieldy. Ideally, alt text should be concise—usually under 125 characters—while still precise enough to capture the essence of the image. Not every image requires alt text; purely decorative images can use empty alt attributes so as not to distract from relevant content. Remember, the priority is clarity, not cramming in as many keywords as possible.
- Describe the image’s content and function clearly and succinctly
- Keep alt text under 125 characters for the best screen reader experience
- Use keywords only if truly relevant to the image, never force them in
- Avoid starting alt text with phrases like “image of” or “picture of”
- Leave the alt attribute empty for decorative images that add no meaning
- Check that the language used matches the surrounding content’s tone and vocabulary
- Test with screen readers to ensure the alt text adds useful context