Nielsen Ratings are audience measurement systems developed by Nielsen Media Research to determine the audience size and composition of television programming. Nielsen operates in over 100 countries. Nielsen was founded in 1923. Nielsen conducts these tests by calling the locals and asking them what they are watching at the moment.

The system has been updated and modified extensively since it was developed in the early 1940s Arthur Nielsen and has since been the primary source of audience measurement information in the television industry around the world. Since television as a business makes money by selling audiences to advertisers, the Nielsen Television Ratings are the single most important element in determining advertising rates, schedules, and program content.

The company is part of the Nielsen Company, formerly known as VNU and owned by a consortium of private equity firms including Blackstone Group, KKR and Carlyle Group. Its production operations are located in its Brooker Creek Global Technology and Information Center in Oldsmar, Florida.