revenues) primarily measures what consumers are watching (and listening to) across most devices: TV, radio, computers, mobile, over-the-top, etc. The company measures consumption of programming and advertising across all distribution points. Nielsen's ratings are used by advertisers and networks to shape the buying and selling of advertising. Major clients include CBS, NBC Universal, News Corporation, and The Walt Disney Company. Nielsen's Watch business measures media in 47 countries that together represent approximately 80% of global advertising spending. Nielsen's digital audience measurement capability is a rapidly growing part of this footprint. Company history Arthur C. Nielsen and the invention of "Market Share" Arthur C. Nielsen founded the AC Nielsen Company in August 1923 with the idea of selling engineering performance surveys. It was the first company to offer market research. The company expanded its business in 1932 by creating a retail index that tracked the flow of food and drug purchases. This was the first retail measurement of its kind and for the first time allowed a company to determine its "share" of the market—the origination of the concept of "market share" Arthur C. Nielsen is credited with coining this business term. Radio and television In 1936, Arthur C. Nielsen acquired the Audimeter, which measured which radio stations a radio had been tuned to during the day. After tinkering with the device for a few years, the company created a national radio rating service in 1942. The company collected information on which stations radios were tuned to in one thousand homes. Then, this survey data was sold to manufacturers who were interested in the popularity of programs and demographic information about listeners for advertising purposes. This was the birth of audience measurement that would become the most well-known part of Nielsen's business when applied to television. Today, these are commonly referred to as "Nielsen ratings". The company began measuring television audiences in 1950, at a time when the medium was just getting off the ground. Just as with radio, a sampling of homes across the U.S. was used to develop ratings. This information was collected on a device that was attached to a television that recorded what was being watched. In 1953, the company began sending out diaries to a smaller sample of homes ("Nielsen families") within the survey to have them record what they had watched. This data was put together with information from the devices. This combination of data