3 Chapter 3: Writing Effective Alt Text
The key principles for creating effective Alt Text center around conciseness, clarity, and relevance. Alt Text should succinctly convey the essence of an image, focusing on descriptive accuracy without interpretation, allowing all users to grasp the intended message or function of visual content. By prioritizing context and omitting redundant phrases like “image of,” content creators can craft Alt Text that not only adheres to accessibility standards but also enriches the user experience. These foundational guidelines ensure that Alt Text serves as a bridge to understanding, making digital environments more inclusive and navigable for everyone.
Key Principles for Crafting Meaningful Alt Text
Conciseness and Clarity: Effective Alt Text should be concise yet descriptive enough to convey the essence of an image. Aim for brevity, ideally under 125 characters, to ensure screen readers present the information efficiently.
Descriptive, Not Interpretive: Focus on describing what is present in the image rather than offering an interpretation. Allow users to draw their own conclusions.
Context Matters: The Alt Text should be tailored to the context in which the image is used. The same image may require different alt text depending on its role in the content.
Omit Redundant Phrasing: Avoid starting Alt Text with phrases like “image of” or “picture of.” Screen readers typically announce images, making such introductions unnecessary and redundant.
Strategies for Describing Images
Informational Images: For images conveying critical information, such as graphs or charts, describe the data or insight the image provides, not just its appearance. For example, “Bar graph showing a 30% increase in solar energy usage from 2010 to 2020.”
Complex Images: For complex images like infographics, provide a brief overview of the key message in the Alt Text and offer a longer description nearby or link to a full description.
Functional Images: When images are used as controls (e.g., buttons), ensure the Alt Text describes the action it performs, such as “Search” for a magnifying glass icon.
Common Mistakes and How to Avoid Them
Being Too Vague: Generic descriptions like “chart” or “photo” offer little value. Be specific about what the image shows and why it’s important.
Over-description: Including every detail can overwhelm the user with information. Focus on the image’s relevance to the content.
Ignoring the User Experience: Consider how the Alt Text will sound when read by a screen reader and how it contributes to the overall understanding of the content.
Neglecting Testing: Regularly test your content with screen readers to understand how Alt Text is interpreted and where improvements are needed.
Activity
Practice writing Alt Text with the following H5P activity.
Understanding Decorative Images
Not all images carry informational value or contribute directly to the content’s meaning. Decorative images, which serve to enhance the visual appearance of a webpage without providing essential information, occupy a unique aspect in the design of accessible content. Understanding how to handle Alt Text for these decorative elements is important for maintaining an accessible and clutter-free experience for users relying on screen readers.
Decorative images can include background graphics, stylized text used purely for visual flair, icons that don’t convey specific actions or information, and any visual elements added to create a certain look or feel rather than to inform. The key question to ask is: “Does this image add information or context necessary to understand the content?” If the answer is no, the image can be considered decorative.
The conventional approach to providing Alt Text for decorative images is to use an empty alt attribute (alt=””). This practice tells screen readers to skip over the image, as it does not contribute to the content’s meaning. By effectively marking decorative images with empty alt attributes, content creators ensure that screen reader users do not have to navigate through irrelevant information. This approach aligns with web accessibility guidelines (e.g., WCAG), reinforcing the importance of these practices.
Activity
Practise your identification of decorative images with this H5P activity.