This paper addresses an overview of "knowledge management" from business management/social science perspectives and information technology perspectives, including ongoing research of "knowledge sharing approach towards information retrieval". We usually use various knowledge when facing practical problems, and transfer it to others for re-use. Such features are investigated for long-time period, and some are characterized and understood by terms such as "SECI model", "the wisdom of crowds", "knowledge-centric" and so forth. Information technology provides several functionalities to enhance knowledge management methodology from usable computer system points of views. Through research on knowledge sharing, some hints are provided this research area. (c) 2008 Elsevier B.V. All rights reserved.