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Alt text 0:34
A 34-second explainer of Alt text, narrated over the same demo you can try yourself.
Try the interactive Alt text demo
What this video covers
Alt text is the written description an image carries for people who can't see it - read aloud by a screen reader, and shown if the image fails to load. Good alt conveys what the image means; bad or missing alt leaves a hole in the page.
With no alt the screen reader had nothing useful to say; with the filename it read out gibberish; with a real description it passed on the actual point of the picture. Same image every time - the only thing that changed was whether someone not looking at it got the meaning or got left out.
