I call it an annotation multiverse because it is a bit like a zillion universes of dialogue in which you can use not only words, but images, animated gifs, video, and soundfiles to make notes on digital, online objects.
This capacity was built into the very first Mosaic graphic browser by its creator Marc Andreeson, but later stripped out. It has taken twenty years to begin to add universal annotation back into the browser.
I, for one, am very glad they did. And by they I mean Hypothesis