What Alt Text Is and Why AI Helps Create It

Think of alt text like a detailed caption that sits invisibly behind every image on the web. When someone using a screen reader (a tool that reads websites aloud) encounters an image, alt text tells them what's there instead of showing the picture.

Here's why it matters: If a website has a photo of a dog running through a park, sighted people instantly see the joy and motion. Someone using a screen reader hears nothing unless there's alt text. The alt text might say: "Golden retriever running through grass in sunny park." Suddenly, they have the same information as everyone else.

Alt text isn't just for blind users. It helps anyone when images won't load, appears in search engines to describe your photos, and makes content searchable. It's basically fairness in action.

Here's where AI changes the game: Writing good alt text is surprisingly hard. It requires you to see the image, understand what's important about it, and write a brief, clear description. That's three separate skills. AI can do this instantly. You upload an image, and it generates a description. Some AI systems are so smart they can identify not just "cat" but "tabby cat sleeping on blue couch in afternoon light."

The AI analyzes the image using computer vision—technology that lets machines "see" and understand visual content. It identifies objects, text, composition, and context, then writes a natural sentence describing what it sees.

Most AI tools generate alt text automatically now. Microsoft Copilot, Google Gemini, and Claude can all do this. Some specialized accessibility tools make it even easier as a one-click process.

One reality check: AI isn't perfect. It might miss subtle context or describe something in a way that's not quite right for your specific use. Always review AI-generated alt text before publishing.

Try this: Find any image online, right-click it, and ask an AI tool to "describe this image in one natural sentence for someone who can't see it." Then try it with a more complex image—a screenshot, a chart, artwork—and see how the AI adapts.