How do networks know how many viewers are tuning in to watch their programming?

what is the best answer to

Question by JC: How do networks know how many viewers are tuning in to watch their programming?
Just curious as to how major networks measure how many viewers are tuning in to watch their various shows/programming. Thanks!


Best answer:

Answer by l'il mama
Just like a phone company knows who you called. Not sure how it works out but someone figures out that crap.



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