Alt Text, explained properly.
What is alt text?
Alt text (short for alternative text) is an HTML attribute that describes the content and function of an image. Its primary purpose is to make images accessible to screen reader users, but it also plays a significant role in on-page SEO, particularly image indexing and semantic relevance.
Why is alt text important?
There are two main reasons to use it: 1. **Accessibility:** users with visual impairments can understand image content through assistive technology. 2. **SEO:** search engines cannot interpret images visually, so alt text helps them understand what each image represents, supporting content relevance and visibility in Google Images.
How alt text supports SEO
Well-optimised images can bring in organic traffic, especially in visual sectors like ecommerce, design and food and drink. It also pairs with good image optimisation habits like compression and modern formats. Accurate alt attributes help search engines contextualise the page, match images to relevant searches and improve accessibility scoring. In Shopify SEO projects, alt text on product photos improves both product page rankings and image visibility.
Writing great alt text
Good alt text is descriptive, concise (ideally under 125 characters), contextual to the image's function, and keyword-friendly only where natural. - Weak: "image123" - Okay: "Dog in park" - Strong: "Golden retriever running through grass with tennis ball"
How to add alt text
In hand-coded HTML: ``` <img src="dog.jpg" alt="Golden retriever running through grass with tennis ball"> ``` CMS platforms like WordPress, Shopify, Wix and Squarespace all include alt text fields in their media managers.
Alt text and website migrations
Alt text is often lost during a website migration, and restoring it page by page can be painful. Build a migration-specific image audit into any move to preserve alt attributes and improve them where needed.
Common mistakes to avoid
- Leaving alt text blank unless the image is purely decorative. - Using identical alt text across multiple images. - Keyword stuffing. - Describing how the image looks without explaining its purpose.
Optimising at scale
For sites with hundreds or thousands of images, tools like Screaming Frog scan for missing alt attributes so you can fix them in bulk. For ecommerce clients on WooCommerce or Shopify, export and import spreadsheets handle alt text updates efficiently.
Alt Text: common questions.
How long should alt text be?
Specific enough to describe the image, short enough to be readable. Typically 5 to 15 words, up to 125 characters. Do not pad with keywords; describe what the image actually shows. Decorative images should have empty alt text (alt=""), not a missing attribute.
Should I include keywords in alt text?
Where genuinely relevant, yes. A product image should naturally include the product name. A stock photo of a person at a laptop probably should not force keywords in. Honest description first, keywords second when they fit.
Does alt text affect rankings?
Indirectly. Alt text helps Google understand image content, which contributes to page topical relevance and image search rankings. The direct effect on text search rankings is small; the effect on image search rankings can be significant for visual products.
What about decorative images?
Use empty alt text: alt="". This tells screen readers the image is decorative and can be skipped. An empty alt is different from no alt and gives the right signal to assistive technology.
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