CRM (Customer Relationship Management) means to focus all business activities on customers. This includes all business functions starting by buying departments and ending by sales departments. In the past years the traditional company perspective has been changed. Reason is the development of the markets from a seller's market to a buyers market. So more and more companies have implemented customer loyalty programs. These programs support companies to retain their present customers. Retaining the present customers is an important issue because it is often much cheaper to retain a costumer than to gain a new one. One of the most popular loyalty programs in Germany for instance is payback.