And why it matters for digital inclusion
Alt text – short for alternative text – is a written description added to an image in digital content. It serves as a substitute for the image when the image cannot be seen: for users who are blind or have low vision and rely on screen readers, for people who have disabled images to save data, and for situations where an image fails to load. Writing good alt text is one of the simplest and most impactful things you can do to make your digital content more accessible. Yet it remains one of the most widely misunderstood practices.
When a screen reader encounters an image without alt text, it either skips it entirely or announces something like ‘image’ or a string of meaningless file code. For a user relying on that technology, the content of the image is simply gone. If the image is decorative, that may not matter. But if the image conveys information, tells a story, or is part of navigation, the absence of alt text creates a real barrier to understanding.
The Web Content Accessibility Guidelines (WCAG) require that all non-decorative images have a text alternative. This is not a technical recommendation – it is a baseline standard for digital inclusion.
The most common mistake in writing alt text is describing how an image looks rather than what it communicates. Alt text should answer the question: what is this image doing here? What would a sighted user understand or feel from seeing it that a non-sighted user would miss if there were no description?
Consider an image of two young people sitting together at a laptop, smiling. A poor alt text might be: ‘Two people at a laptop.’ A better alt text might be: ‘Two young people collaborating on a project, looking engaged and positive.’ The second version conveys the purpose of the image – to communicate inclusion, engagement, and collaborative work – rather than just its literal content.
Keep it concise but complete. Most alt text should be under 125 characters. Screen readers often cut off longer descriptions. If an image requires a longer explanation, consider adding a caption or describing it in the surrounding body text.
Do not start with ‘Image of’ or ‘Photo of.’ Screen readers already announce that something is an image. Starting your alt text with this phrase is redundant.
Include text that appears in the image. If an image contains words – a poster, a sign, a screenshot with text – that text must be included in the alt text. Screen readers cannot read text embedded in images.
Leave decorative images empty. If an image is purely decorative and adds no information – a background pattern, a divider, a generic stock photo used only for visual interest – use an empty alt attribute (alt=””). This tells the screen reader to skip it entirely, which is the correct behaviour.
Be specific about charts and graphs. For data visualisations, your alt text should convey the key finding or trend, not just describe the chart type. Instead of ‘Bar chart of website users,’ write ‘Bar chart showing a 40% increase in website users between 2023 and 2025.’
Context matters. The same image may need different alt text depending on its context. A photo of a wheelchair user on your about page (‘Member of our team in front of our office’) requires different alt text than the same photo used in an article about accessible venue design (‘Person using a wheelchair navigating an accessible entrance ramp’).
Adding alt text should become a routine part of how you publish any digital content – articles, social media posts, presentations, email newsletters, and documents. Most content management systems, social media platforms, and office tools now include an alt text field when you upload an image. The field exists for a reason. Use it.
Good alt text is a small act with significant consequences. It means that a young person using a screen reader can access your content on equal terms with everyone else. That is precisely what digital accessibility is about.
