Various definitions of the term "quality" in the literature of the subject suggest that quality is the capacity of a product (physical product or service) to satisfy the buyer's needs. In consequence, the degree of fit between the product offered and the customer's expectations should be the basic criterion of quality assessment. It is the customer who ultimately endorses quality, expressing his views through his buying decisions. Buyers' behaviour is governed by their needs, understood as the gap perceived between the status quo and the desired or preferred state of affairs. Thus a service is of appropriate quality if it is provided in a manner at least adequate to the recipient's expectations.

The sources of discrepancy between a service expected and a service obtained by the customer have been identified and presented in the service quality model developed by V. A. Zeitmal, A. Parasuramana and L. Berry. The expectations of banks' customers relate to the range of services offered and the manner in which they are rendered, but also to the organisation itself, as the customer-organisation interaction requires mutual trust. The human factor is of paramount importance to the quality of banking service. How a customer perceives a banking product is often determined by the treatment he gets from the bank staff; high quality service is one of the crucial elements of a bank's capability to retain customers.

Unfortunately, both anecdotal evidence and research show that the service of individual customer in Polish banks leaves a lot to be desired. This lack of emphasis on meeting customers' expectations will inevitably result in their dissatisfaction, and ultimately in decisions to change the bank. The first signs of this trend have already been observed. Respondents asked about the reasons to change the bank where they hold their current accounts typically indicate low quality of personal service. In their efforts to improve matters, banks could benefit greatly from the concept of internal marketing.