Net Promoter Score (NPS) is a customer loyalty metric that measures how likely customers are to recommend a company, product, or service to a friend or colleague, calculated as the percentage of promoters minus the percentage of detractors on a single 0–10 survey question.

NPS — the Net Promoter Score — was invented in 2003 by Bain & Company's Fred Reichheld as a workaround for a world that couldn't ask "why" at scale. The single 0–10 question "How likely are you to recommend us?" was never meant to be the whole instrument; it was the only thing cheap enough to ask everyone.