Customer service …provision of service to customers before, during and after a purchase

According to Turban et al. (2002), “Customer service is a series of activities designed to enhance the level of customer satisfaction – that is, the feeling that a product or service has met the customer expectation." Its importance varies by products, industry and customer; defective or broken merchandise can be exchanged, often only with a receipt and within a specified time frame. Retail stores will often have a desk or counter devoted to dealing with returns, exchanges and complaints, or will perform related functions at the point of sale; the perceived success of such interactions being dependent on employees.
From the point of view of an overall sales process engineering effort, it plays an important role in an organization's ability to generate income and revenue. From that perspective, Customer service should be included as part of an overall approach to systematic improvement. A Customer service experience can change the entire perception a customer has of the organization