NLSN

Nielsen Holdings Plc

A maker of audience measurement and consumer data, Nielsen is best known for the "Nielsen ratings" that tell TV networks, advertisers, and retailers what people watch, listen to, and buy. It was founded in Chicago in 1923 by engineer Arthur C. Nielsen, who coined the term "market share" by auditing store shelves. Fun fact: the famous Audimeter device that tracks viewing was invented for radio in 1942, recording listening habits on waxed paper tape before it ever measured television.