Net promoter score (NPS) is a market research metric that is based on a single survey question asking respondents to rate the likelihood that they would recommend a company, product, or a service to a friend or colleague. The NPS was developed by Fred Reichheld and has been widely adopted by large companies, initially being popularized in Reichheld's 2003 Harvard Business Review article. Methodology. The NPS assumes a subdivision of respondents into "promoters" who provide ratings of 9 or 10, "passives" who provide ratings of 7 or 8, and "detractors" who provide ratings of 6 or lower.
https://en.wikipedia.org/wiki/Net_promoter_score