NPS is a tool which is relatively simple to understand and implement. Essentially it is a metric that reflects how companies and employees treat their customers. Once determined it can facilitate change and improved performance.
The method used is to ask customers one simple question; "How likely is it that you would recommend Company X to a friend or colleague?" and respond with a rating scale of 0-10 points. Based on those results, Net Promoter then divides your customers into 3 categories: Promoters (score 9-10): These are your most loyal customers. They keep returning, buy more and continually refer others. Passives (score 7-8): These customers are satisfied but generally unenthusiastic and not particularly loyal to your brand. Detractors (score 0-6): Are unhappy, inhibit growth, and can damage your brand's reputation through bad reviews and negative word of mouth.