Nielsen ratings

Nielsen TV ratings (commonly referred to as "Nielsen ratings") are the audience measurement systems operated by Nielsen Media Research that seek to determine the audience size and composition of television programming in the United States using a rating system.

Nielsen Media Research was founded by Arthur C. Nielsen, a market analyst who started his career in the 1920s with marketing research and performance analysis. The company expanded into radio market analysis in the late 1930s, culminating in the Nielsen Radio Index in 1942, which was meant to provide statistics as to the markets of radio shows. The first Nielsen ratings for radio programs were released the first week of December 1947. They measured the top 20 programs in four areas: total audience, average audience, cumulative audience, and homes per dollar spent for time and talent.

In 1950, Nielsen moved to television, developing a ratings system using the methods he and his company had developed for radio. That method became the primary source of audience measurement information in the US television industry.