In the last few years there has been a change from a product-oriented to a customer-oriented strategy. The philosophy, which is the basis for this new orientation is called Customer Relationship Management. Especially in the field of the new medias and there in the Internet such new strategies will be used. CRM has been adapted for these new media as electronic CRM. eCRM consists of techniques, which support the possibility of extensive analyses of data. A special field in the field of these new media and especially in the Internet, where eCRM-techniques are heavily used. This group of users, which combine themselves to communities, are a perfect target-group for the use of CRM-techniques, because of the service-focused and customer-oriented offerings of attendances. In the theoretical part of this thesis the basis and definitions of Customer Relationship Management and additional technologies, namely Knowledge Management, Electronic Customer Relationship Management will be looked at. Generally the coherences between the technologies will be discussed. A cooperation of all these technologies is the basis for the deployment of eCRM-strategy. Techniques out of the field of eCRM constitute the possibility of additional use of a strategy. In the practical part based on the awareness of the theoretical part and constitutive on the existing search a Case study of eCRM application will be discussed. The focus has been set on the formation and the operation of a the application and the use of a eCRM-strategy and additional parts such as sales processes would be included, based on all fields of the theoretical part of the thesis. Customer relationship management is a business strategy to select and manage customers to optimize long-term value (Oxford University: Lee, 2000). In today's business climate, many companies recognize the lifetime value of customers, and how customer service can establish and maintain relationships with each customer, especially through on-line communication. To continually seek out new customers and to replace lost customers is an expensive proposition. Thus, it is imperative that a business develops positive lasting relationships with customers. This study reviews the concept of CRM and how electronic eCRM can be an important means of customer communication. It also discusses the components of successful CRM and eCRM implementation and introduces factors that affect the performance. The thesis concludes with a discussion of the consequences of eCRM and its future in today's evolving business world.