Alt Attribute

The alt attribute, also known as the “alt tag” or “alt text,” is a specification within the HTML code of an image tag that provides a textual alternative for the image. This attribute is essential for both accessibility and SEO.

Application in SEO:

From a technical SEO perspective, the alt attribute serves several critical functions. Firstly, it improves web accessibility by describing the content and function of images to users who may be visually impaired and using screen readers. Secondly, it provides a contextual clue to search engine algorithms about the subject matter of the image, which can improve the relevance of a webpage to specific queries and enhance the overall SEO performance.

Moreover, the alt text acts as a critical signal to search engine algorithms, granting them insight into the subject matter of an image. This added layer of information not only aids in classifying the image content but can also bolster the relevancy of a webpage for targeted search queries. As search engines strive to contextualize and interpret the content of webpages, the presence of well-crafted alt attributes can enhance the overall SEO performance, contributing to better indexing and visibility within search results.

Optimization tips:

  • Ensure each image on a webpage has a relevant, concise description in its alt attribute.
  • Use keywords judiciously within the alt text, relating them directly to the image content to avoid keyword stuffing.
  • Avoid using alt attributes for purely decorative images where a description is not necessary.
  • For e-commerce sites, include product details such as brand, model, and other relevant information.

Technical considerations:

  • Alt text should ideally be kept short, around 125 characters, to ensure compatibility with screen readers.
  • Special characters should be avoided as they may not be interpreted correctly by screen readers.
  • If an image is also a link, the alt text should describe the link destination rather than the image content.

Remember, the alt attribute not only strengthens SEO efforts but is also a critical component of a website’s compliance with web accessibility guidelines.


Can you give an example of effective alt text for an e-commerce product image?

Effective alt text for an e-commerce product image should concisely describe the product, incorporating elements such as the product type, brand, model, color, and size when relevant. For example, alt text like "Samsung Galaxy S21 Ultra smartphone in phantom black" gives a clear description and is likely to include keywords that potential customers might use to search for this product.

How important is the alt attribute for images in terms of SEO?

The alt attribute is crucial for SEO as it provides search engines with context about the content of an image. When images have relevant alt text, it can help the images rank in image search results and also contribute to the overall topic signals of the webpage they are on. Additionally, alt attributes enhance web accessibility for visually impaired users, which search engines consider a positive attribute of a webpage.

Should all images have an alt attribute, even if they are purely decorative?

Not necessarily. If an image is used solely for decorative purposes and does not contribute to the content or meaning of the page, it is appropriate to leave the alt attribute empty. This can be achieved by using an empty alt tag (alt=""), which signifies to screen readers that the image can be ignored. This approach helps prevent screen readers from focusing on irrelevant content, improving the browsing experience for users who rely on them.

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