Rolodex

thumb|A Rolodex file used in the 1970s A Rolodex is a rotating card file device used to store a contact list. In this usage, it has generally come to describe an effect or characteristic of the small-world network of a business's investors, board of directors, or the value of a CEO's contacts, or in organizational structure. Models have been exhibited in the Smithsonian Institution.

==History== The Rolodex was invented in 1956 by Danish engineer Hildaur Neilsen, the chief engineer of Arnold Neustadter's company Zephyr American, a stationery manufacturer in New York. Neustadter was often credited with having invented it. First marketed in 1958, it was an improvement to an earlier design called the Wheeldex. Zephyr American also invented, manufactured and sold the Autodex, a spring-operated phone directory that automatically opened to the selected letter; Swivodex, an inkwell that did not spill; Punchodex, a paper hole puncher; and Clipodex, an office aid that attached to a stenographer's knee. Rolodex also marketed non-rotary (linear) tub-like card-file systems using the same cards (size and notches) as the rotary files.