What is Alt text?
Alt text, or alternative text, is the description of an image in words. It serves accessibility first: someone using a screen reader hears the description instead of the image. It also helps the network understand what the post is about, which influences where it appears in search and recommendations. Instagram generates an automatic alt text, almost always a poor one; writing your own, saying what the image shows and what the slide text says, is quick and pays off on both fronts.