The document discusses the Net Promoter Score (NPS) metric for measuring customer loyalty and satisfaction. NPS is based on asking customers how likely they are to recommend a company to others. It categorizes customers as Promoters, Passives, or Detractors. A company's NPS is calculated by subtracting the percentage of Detractors from the percentage of Promoters. Research shows that companies with higher NPS scores experience greater growth rates. The document provides examples of how various companies use NPS and statistical analysis to improve customer experience and drive business growth.