Alt Attribute for Web Accessibility – The Essential Guide
What is the Alt Attribute?
Definition and Purpose
The alt attribute is an HTML attribute that provides alternate text for images, enhancing accessibility and offering context for users utilizing screen readers.
The alt attribute is used to specify alternative text for images, image maps, and other elements.
The attribute values are supported by the following tags: <area>, <img>, <input>, and <applet>.
Historical Context and Evolution of the Alt Attribute
The alt attribute has a rich history that dates back to the early days of the web. In 1993, the World Wide Web Consortium (W3C) introduced the alt attribute as part of the HTML 2.0 specification. The primary purpose of the alt attribute was to provide a text alternative for images, allowing users with visual impairments to access the content.
Over the years, the alt attribute has undergone significant changes and improvements. In 1997, the W3C introduced the HTML 4.0 specification, which included guidelines for using the alt attribute to improve accessibility. The specification emphasized the importance of providing a concise and accurate description of the image content.
In 2008, the W3C introduced the HTML 5 specification, which further refined the guidelines for using the alt attribute. The specification emphasized the importance of providing a text alternative for all images, including decorative images, and introduced the concept of the “empty alt attribute” (alt=””) for decorative images.
Today, the alt attribute is an essential component of web accessibility, and its use is widely adopted by web developers and designers. The evolution of the alt attribute has played a significant role in improving the accessibility of the web, and its continued development will ensure that the web remains accessible to all users.
Benefits of the Alt Attribute
Improving Accessibility and User Experience with Screen Readers
The term ‘alt tags’ is a commonly misused term that actually refers to the ‘alt attribute’ used in image tags. The alt attribute provides a text alternative for non-text content, making it accessible to users with visual impairments.
Alt text is read aloud by screen readers, allowing users to understand the content of images.
The alt attribute improves the overall user experience by providing a description of the image.
Boosting Image Search Rankings
Incorporating relevant images is crucial in optimization strategies for higher search rankings. The alt attribute helps search engines understand the content of an image, making it more likely to be included in relevant search results.
Optimized alt text can significantly increase your website’s visibility in image search, driving more traffic to your site.
Alt text offers you another opportunity to include your target keyword and gives context clues to bots programmed to understand your website content.
How to Use the Alt Attribute
Adding Alt Text to Images
The image tag is used in HTML code to display images on webpages, using the format < img src=”image.jpg” alt=”image description”>. The src attribute within the image tag indicates the source of the image to be displayed.
Many content management systems will have options to add and edit alt text when you’re uploading your content.
You can right-click any image and “inspect” to open up Chrome DevTool and look for the img alt attribute.
Best Practices for Alt Text
Writing Optimized Alt Text
Write concise alt text that is descriptive yet brief, ensuring it is effectively conveyed through assistive technologies.
Use relevant keywords from research in alt text for better search relevance.
Avoid overstuffing with keywords, as it can detract from user experience and search engine perception.
Skip redundant phrases, such as “image of” or “picture of”.
Handling Decorative Images
For purely decorative images that do not add information to the content, it is best to use an empty alt attribute (alt=””).
This signals screen readers to skip the image.
Use CSS for purely decorative images, not HTML.
Special Cases for Alt Text
Logos and Branding
For logos, especially logos which are repeated, it is sufficient to identify which logo it is, not necessarily fully describe it.
Use a brief and accurate description of the logo’s content or purpose.
Links and Buttons
For images used as navigational elements to trigger functions such as printing, uploading, or saving, the alt text should describe the destination or function, not the image.
Use a brief and accurate description of the link’s content or purpose.
Common Mistakes to Avoid
Improper Uses of Alt Text
The alt attribute should be used ONLY to describe an image.
Avoid using alt text to describe the image’s file name or format.
Avoid using alt text to provide redundant information, such as a caption that is already provided in the surrounding text.
Legal Implications and Compliance
The use of the alt attribute has significant legal implications, particularly in the context of web accessibility. In the United States, the Americans with Disabilities Act (ADA) requires that all public websites be accessible to users with disabilities. The use of the alt attribute is a critical component of web accessibility, and failure to provide adequate alt text can result in legal action.
In 2010, the U.S. Department of Justice issued a ruling that websites must be accessible to users with disabilities, including those who are blind or have low vision. The ruling emphasized the importance of providing alternative text for images, including the use of the alt attribute.
In addition to the ADA, other countries have their own accessibility laws and regulations that require the use of the alt attribute. For example, the European Union’s Accessibility Act requires that all public websites be accessible to users with disabilities, including those who are blind or have low vision.
To ensure compliance with these laws and regulations, web developers and designers must provide adequate alt text for all images, including decorative images. The use of the alt attribute is a critical component of web accessibility, and failure to comply can result in legal action.
Tools and Resources for Testing Alt Text
Ensuring that your alt text is effective and compliant with accessibility standards is crucial. Fortunately, there are several tools and resources available to help you test and optimize your alt text:
WAVE Web Accessibility Evaluation Tool: This free online tool evaluates the accessibility of a website, including the use of alt text. It provides visual feedback about the accessibility of your web content by injecting icons and indicators into your page. (WAVE)
Lighthouse: An open-source, automated tool for improving the quality of web pages. It has audits for performance, accessibility, progressive web apps, SEO, and more. Lighthouse can be run in Chrome DevTools, from the command line, or as a Node module.
Accessibility Checker: Another free online tool that evaluates the accessibility of a website, including the use of alt text. It provides detailed reports and suggestions for improving accessibility.
JAWS Screen Reader: A popular screen reader that can be used to test the accessibility of a website, including the use of alt text. It reads aloud the content of a web page, allowing you to experience your site as a visually impaired user would. (JAWS)
NVDA Screen Reader: A free, open-source screen reader for Windows. It can be used to test the accessibility of a website, including the use of alt text. NVDA is a great tool for developers to ensure their websites are accessible to all users.
These tools and resources can help web developers and designers ensure that their websites are accessible to all users, including those who are blind or have low vision.
Case Studies or Examples of Effective Alt Text Usage
Effective alt text usage can significantly enhance the accessibility and user experience of a website. Here are a few real-world examples of how well-known websites implement alt text:
The New York Times: The New York Times uses alt text to provide detailed descriptions of images, including photographs and graphics. For instance, an image of a sunset might have the alt text “A sunset over the ocean, with the sun dipping below the horizon.” This descriptive alt text helps screen reader users visualize the image content.
Amazon: Amazon uses alt text to describe product images, ensuring that all users can understand the product features. For example, an image of a product might have the alt text “A black iPhone with a 6.1-inch screen and 12-megapixel camera.” This approach not only aids accessibility but also improves the site’s SEO.
The National Gallery of Art: The National Gallery of Art provides alt text for artworks, including paintings and sculptures. For example, an image of a painting might have the alt text “A painting of a woman in a red dress, standing in front of a landscape.” This detailed description helps users with visual impairments appreciate the artwork.
These examples demonstrate the importance of providing accurate and descriptive alt text for images. By doing so, you can improve the accessibility of your website and ensure a better user experience for all visitors.
Technical Considerations With Web Accessibility
Supported Browsers
The HTML alt attribute is supported by most modern browsers, including Google Chrome, Mozilla Firefox, and Microsoft Edge.
The alt attribute is required for all <img> tags in HTML5.
Conclusion
Summary and Key Takeaways
The alt attribute is an essential element for web accessibility, providing alternative text for images and improving user experience.
Optimized alt text can boost image search rankings and drive more traffic to your site.
Use relevant keywords, avoid overstuffing, and handle decorative images correctly to ensure effective alt text.
