How to Write Effective Alt Text: A Guide to Accessible Web Content

Alt text (short for alternative text) plays a critical role in making websites accessible to all users, especially those who rely on assistive technologies like screen readers. It serves as a text-based description of non-text elements, such as images, icons, and charts, allowing visually impaired users to understand and engage with content that they cannot see.

Alt text is required for any meaningful visual content on a web page. It describes images, logos, buttons, infographics, and interactive elements to ensure that these are perceivable by everyone. By following the principles of the Web Content Accessibility Guidelines (WCAG), alt text makes websites more inclusive while also improving user experience and SEO (Search Engine Optimisation). This blog post will guide you through the essential considerations for writing effective alt text.

What Types of Descriptions Does Alt Text Include?

Alt text can be used in several contexts, including:

Images

Informative images, such as product photos or illustrations, need descriptive alt text to explain their content.

Buttons and Icons

Interactive elements like buttons and icons require alt text that explains their function, such as "Submit" or "Search."

Graphs and Charts

These need a summary of the key information they present, ensuring that users who can't see the visuals still understand the data.

Logos

Company logos should be described in the alt text to convey the brand name and identity.

However, decorative images, which don't provide meaningful information, should be marked with an empty alt attribute (alt="") so screen readers can skip them.

Why is Alt Text Necessary?

Alt text ensures that users with visual impairments or those using screen readers can fully access and comprehend the content on a webpage. Without alt text, they might miss out on important details or context, leaving them unable to navigate or use the site effectively. This not only improves accessibility but also enhances the overall user experience. It’s also important for users in low-bandwidth situations, where images might not load properly, as alt text provides a backup description.

In addition, alt text supports SEO by allowing search engines to understand what an image represents, improving the discoverability of your content.

Areas to Consider When Writing Alt Text

When crafting effective alt text, there are several factors to keep in mind:

Purpose of the Image

Is the image conveying essential information or just serving a decorative purpose? Understanding the image's role helps determine whether you need descriptive alt text or if it can be omitted.

Context of the Image

Alt text should be tailored to the context in which the image appears. For example, an image of a dog might have different alt text depending on whether it’s used on a veterinary website ("Golden retriever at a vet clinic") or an adoption page ("Golden retriever available for adoption").

Audience Needs

Consider the needs of your users. For example, a technical diagram might require more detailed alt text for a professional audience but could be simplified for a general audience.

How to Write Effective Alt Text

Here are some best practices for writing alt text that is clear, concise, and informative:

Be Descriptive but Concise

Alt text should describe the image’s content succinctly, but also effectively convey its meaning. You don’t need to provide a long-winded description; aim for a brief sentence or phrase that captures the essence of the image. For example, instead of "A photo of a brown dog playing with a red ball in a green park on a sunny day," you can write, "Brown dog playing with a ball in the park."

Don't be Repetitive

If the surrounding text or a caption already provides the necessary information about an image, you don’t need to repeat it in the alt text. The goal is to provide new, relevant details that aren’t otherwise available. For instance, if a caption already says "Our team at the 2022 conference," the alt text could simply say "Group photo of the team" rather than restating the year or event.

Focus on Function for Interactive Elements

For buttons and other functional elements, the alt text should describe the action they perform, not just what they look like. For example, alt text for a search icon should say "Search" rather than "Magnifying glass”, because it explains the icon's purpose rather than its appearance.

Keep it Simple!

Alt text should be clear and easy to understand. Avoid complex language or technical jargon that might confuse users. Instead, use simple, straightforward descriptions.

Conclusion

Writing effective alt text is key to ensuring your website is accessible and inclusive. By providing descriptive, context-appropriate text alternatives for images and interactive elements, you ensure that users of all abilities can access and engage with your content. Keep in mind the image’s purpose, avoid redundancy, and focus on clarity. In doing so, you not only improve accessibility but also enhance usability and search engine visibility. Thoughtful alt text brings us one step closer to an inclusive web experience for everyone.