Net Promoter Score

A customer loyalty metric based on one question: "How likely are you to recommend us to a friend?" Scores 0-6 are detractors, 7-8 passives, 9-10 promoters. NPS = % promoters minus % detractors.

NPS is the fastest single-number read on customer sentiment. Companies with high NPS grow through word of mouth; low NPS signals fundamental product or experience problems to fix urgently.

A founder surveys her course students: 65% score 9-10, 10% score 0-6. NPS = 55. Industry average is 43. Her strong NPS explains why 40% of new students come through referrals.