The Net Promoter Score (NPS) is a customer loyalty metric developed by Fred Reichheld and Bain & Company, introduced in a 2003 Harvard Business Review article. It is one of the most widely used customer satisfaction measures in business.
Customers are asked a single question: 'How likely are you to recommend [company/product] to a friend or colleague?' on a 0–10 scale. Responses are categorised as: Promoters (9–10), Passives (7–8), Detractors (0–6). NPS = % Promoters − % Detractors.
NPS varies significantly by industry — a score of 30 in banking may be excellent; the same score in technology is mediocre. Compare within industry rather than against absolute benchmarks.