Knowledge Management enables a learning community to learn more effectively. Knowledge Management and Knowledge Management Systems are very important for any multinational organization. In this paper we have tried to study the different aspects of Knowledge Management Systems and relevance of KMS in multinational organization. Key concepts of Knowledge Management are knowledge learning, knowledge creation or knowledge discovery and knowledge sharing. All these concepts are complex in nature. The most important area of Knowledge Management is Tacit Knowledge. Unlike most other management tools, knowledge management encloses every individual in the organization cutting across departments, functions and business units. In order to make these concepts easy Knowledge Management systems are being used by multinational corporations. Knowledge Management Systems helps organizations in creation of knowledge repositories, improving knowledge access, enhancing the knowledge environment and managing knowledge as an asset. In this paper we have described that how Knowledge Management System is an integral part of Knowledge Management process as it helps in knowledge creation & knowledge sharing. The paper also describes that how Tacit & Explicit knowledge is shared by using different types of knowledge management systems e.g. document management system and content management system and also the role of Information Technology is sharing of both Tacit & Explicit knowledge has been described. We have discussed two methods for knowledge creation i.e. 1. Mechanisms to Discover or Create Tacit Knowledge through socialization process and 2. Technologies to Discover or Create New Explicit Knowledge through Data Mining (DM)/Knowledge Discovery in Databases (KDD). This paper has tried to explain the process of knowledge creation with the help of two cases of different multinational organizations. Thus we can say that KMS is Social/Structural mechanisms (e.g., mentoring and retreats, etc.) for promoting knowledge sharing and Leading-edge information technologies (e.g., Web-based conferencing) to support KM mechanisms. Knowledge management systems (KMS) are the synergy between social/structural mechanisms and latest IT technologies.