How is "share" defined in the context of audience measurement?

In the context of audience measurement, "share" specifically refers to the percentage of people watching a particular program compared to the total number of people who are available to watch at that time. This metric provides insight into how well a program is performing among the audience that is actively watching television during its broadcast period, rather than the broader context of total viewers or potential viewers.

Understanding share is crucial for networks and advertisers, as it highlights the program's effectiveness in capturing the attention of the audience that is likely to be watching at that given moment. This is distinct from other metrics, such as total viewership, which may include those who watched at a later time or across different platforms, or loyalty metrics that assess how committed viewers are to a program overall.