TV ratings measure the popularity of television programs by estimating the number of viewers watching a show. These ratings help networks and advertisers understand audience preferences and determine how much to charge for commercial slots. Ratings are typically collected through surveys and electronic devices that track viewing habits. The most common rating system in the United States is managed by Nielsen Media Research. They provide data on various demographics, such as age and gender, allowing networks to tailor their content and advertising strategies. Higher ratings often lead to longer show runs and increased investment in production.