Customer satisfaction is a technique that defines a series or methods and models aiming at measuring customer satisfaction, namely the gap between the expectations of a product / service before the “consumption experience” and the capacity of the product / service to meet or surpass those expectations afterwards. This is why the concept of customer satisfaction is strictly connected to the idea of quality of a product / service, or better of the perceived quality. Questionnaires can be on paper or electronic device, self-completed or administered, face-to-face or on the phone, depending on the Client’s needs, the target to be involved, the type of product / service, etc.