In the context of UI components it has taken on the connotation that it mainly handles interactivity, state, performance, accessibility, cross-platform support and similar functional aspects, while leaving decisions about the visual design to you.

EDIT: And it does allow you to customize both styling and markup, as far as I understand.

I've read your post and the parent several times and I still can't understand what you mean by "it".

First “it” = the term “headless”

Second “it” = the UI component branding itself as “headless”

Third “it” = tiptap