How many college students today ever flip through trays of library catalogue cards? Some of them may never have used an actual tabbed file. But the tab as an information technology metaphor is everywhere in use. And whether our tabs are cardboard extensions or digital projections, they all date to an invention little more than a hundred years old. The original tab signaled an information storage revolution and helped enable everything from management consulting to electronic data processing.

The tab's story begins in the Middle Ages, when the only cards were gambling paraphernalia. Starting in the late 14th century, scribes began to leave pieces of leather at the edges of manuscripts for ready reference. But with the introduction of page numbering in the Renaissance, they went out of fashion.