A thousand years before the internet, rabbis used annotations to break down ancient teachings in the Talmud. Early newspapers were printed with wide margins and extra pages, so readers could add their own thoughts before passing the paper to others. Modern university students circle, highlight and scribble in rented textbooks, taking advice and study tips from the borrowers before them.
As written media has evolved throughout history, so have the annotations alongside it. As brands and media companies are beginning to offer this kind of content interaction to their users online, annotations are primed to fundamentally change the way we experience digital content.