Net Promoter Score is an index that measures customer happiness. A lot of companies use it also as an indicator of growth. The primarly purpose of the NPS is to evaluate customer loyalty to a brand or company and to gather actionable customer feedback.
The NPS is calculated based on responses to a single question:
On a scale of 0-10, How likely is it that you would recommend our company/product/service to a friend or colleague?
People who responds 9 t0 10 are called Promoters
People who responds 7 to 8 are called Passives
People who responds 0 to 6 are called Detractors