We wrote a bunch of words today! A bunch of them specifically in a fediverse thread about obstacles people face to adding image descriptions riffing off the essay "Laziness Does Not Exist" by Devon Price.
...kind of fediverse inside baseball, all things considered, but now our wrists are sending "hey, you might wanna chill a little" signals, so we're not gonna write a lot more here. So you get the link instead. :P
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Okay, also: if you're using the HTML editor to write your Dreamwidth posts, the key is <img src="[image URL]" alt="[text to display if image doesn't load]" title="[text to display when mouse hovers over image]">
. If you use Dreamwidth's image hosting, the HTML it gives you to copy gets auto-filled with the "Title" in the mouseover and the "Short Description" in the alt text.