Do Background Images Need Alt Tags? A SEO Guide for Web Developers

As a SEO expert, it is vital to understand the intricacies involved in providing proper accessibility and SEO optimization for all types of images used on websites. While the question of whether background images need alt tags is often a point of confusion, the answer is quite straightforward.

Understanding Alt Tags and Their Importance

Alt tags, or alt attributes, are crucial for accessibility and SEO. They provide alternative text descriptions for images that cannot be loaded or viewed, such as in cases of slow internet connections, when image files are corrupted, or for users who rely on screen readers. Alt tags improve web accessibility, enhance user experience, and can significantly contribute to a website’s search engine rankings.

Do Background Images Need Alt Tags?

According to Google's guidelines, any image that is inserted directly into the HTML code (using the tag) requires an alt tag. However, when a background image is defined in CSS, it does not need an alt tag. Here’s a detailed explanation of why.

HTML-Sourced Background Images

When an image is included in the src attribute of an tag, the alt tag is a mandatory requirement. This is because screen readers and search engine crawlers may treat background images the same as other visible elements on a webpage. In these cases, the alt tag helps to provide meaningful context and ensure that the content is accessible and descriptive.

CSS-Sourced Background Images

On the other hand, when an image is used as a background in CSS, it is not visible or interactable on its own. Instead, it provides visual styling instead of conveying meaningful information. For example, consider the following CSS:

.bg-image {  background-image: url('');  background-size: cover;  width: 100%;  height: 300px;}

Here, '' is a background image that serves purely aesthetic purposes. Since this image doesn't provide any meaningful information, it doesn’t need an alt tag.

Best Practices for SEO and Accessibility

While background images in CSS do not require alt tags, there are several best practices to consider:

1. Descriptive Alt Tags for HTML-Sourced Images

If you are using images that provide important information or context, make sure to include descriptive alt text. For instance, if a gallery page has images that describe products, the alt text should include the product name and relevant details to assist screen readers and search engine crawlers.

2. Properly Naming Image Files

Naming your images effectively can also enhance SEO. Use descriptive file names that include relevant keywords, as these names can contribute to your search engine rankings and provide additional context for search engines.

3. Using Semantic HTML

By using semantic HTML, you can structure your content in a way that is both accessible and search engine friendly. For instance, use figure and figcaption tags for images that are part of the content rather than mere decorative elements.

Conclusion

In summary, while background images in CSS do not require alt tags, it is important to understand the requirements and best practices for all types of images. Alt tags are a must for images included in the HTML code but can be omitted for purely decorative images defined in CSS. Understanding these guidelines can help you ensure that your website is fully accessible and optimized for both users and search engines.

Related Keywords

background images alt tags SEO HTML CSS

References

Google Developers - Alt Tag Web Content Accessibility Guidelines (WCAG) SEOMoz - Topical Authority