Nowadays, many technologies that have been traditionally used for knowledge management are used in e-learning systems. This chapter explores some fundamental knowledge management technologies that have been applied to e-learning systems, including collaboration technologies, Semantic Web, information retrieval, and information visualization. The focus of this chapter, however, is the Semantic Web and its related topics such as metadata and ontology, since it is now a new trend of the e-learning market. Instead of simply listing these technologies, this chapter provides an in-depth analysis and comparison among them. We hope that after reading this chapter, you will understand the major knowledge management technologies used in e-learning and will be able to choose the proper technologies for different contexts or requirements.