Alt text provides written descriptions of images so screen reader users hear what's on the page instead of just the filename or nothing at all. When AI generates this text automatically, it makes visual content accessible at scale without requiring every creator to manually write descriptions—though human review ensures accuracy and context are preserved.
Think of alt text like the audio description track on a movie. When the screen goes silent and a narrator explains what's happening on screen, that's describing visual information for people who can't see it. Alt text does exactly that for images—it's a hidden sentence or two that describes what's in a photo, diagram, or graphic.
Here's the invisible magic: when someone using a screen reader (a program that reads everything on a page out loud) encounters an image, the screen reader announces the alt text instead of saying "image" or skipping it entirely. Without alt text, a blind person browsing your website only hears "image" and learns nothing about what that image shows.
Writing good alt text is surprisingly hard. It needs to be specific enough to be useful but concise enough to read naturally. "Photo of dogs" isn't enough context. "Golden retriever and black Lab playing tug-of-war with a rope toy in a grassy yard" gives actual information.
AI can analyze an image in seconds and generate descriptions that are both accurate and naturally worded. It identifies not just what's in the image (a dog) but context (what the dog is doing, what mood the image conveys, what details matter). The AI has been trained on thousands of examples of good descriptions, so it knows what level of detail helps without overloading.
AI excels at straightforward images: photos of objects, scenes, activities, and people. It struggles with abstract art, complex charts, or images where the meaning depends on surrounding text. It also sometimes makes assumptions—a photo of someone might incorrectly guess their emotion or identity.
This is why AI alt text usually works best as a starting point. You review it, make corrections, and adjust based on context. On your own documents, this saves hours of manual writing.
Try this: Find an image online that matters to you. Describe it aloud to someone in one clear sentence—what would someone need to know about this image if they couldn't see it? That's alt text thinking. Then use an AI image analyzer tool to see how close its description is to yours.
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