It's not a thing, this is just a term made up on the spot by the author of this article to describe a component library that has no built-in style.
"What does it even do then" you ask. It implements basic accessibility patterns so you only deal with high level UI elements and not have to worry about having the correct `role-` or `aria-` attributes. That and composite elements such as tabs or modals
Why no style? Most product teams have a design system and they actually overwrite the style of component libraries anyway. So better to have component libraries without style, less bloat.
HeadlessUI is one of the newcomers, with a lot of name recognition due to its affiliation with the wildly popular library Tailwind. The term has been around much longer. The first commit of the awesome list was over 3 years ago, and I suspect the term was already fairly established at that point: https://github.com/jxom/awesome-react-headless-components/co...
"What does it even do then" you ask. It implements basic accessibility patterns so you only deal with high level UI elements and not have to worry about having the correct `role-` or `aria-` attributes. That and composite elements such as tabs or modals
Why no style? Most product teams have a design system and they actually overwrite the style of component libraries anyway. So better to have component libraries without style, less bloat.