This chapter reviews some of the most important and useful concepts and models developed in or for KM. The review is organised on the basis of a model of KM as the interplay between people, processes and technology, supported by organizational structures. This stems from a philosophy that the people and technological aspects of KM always need to be balanced appropriately. Adding the content of the knowledge to this model yields the five sub-sections of the chapter. Content aspects cover tacit and explicit knowledge and the SECI model. Process aspects include KM maturity models and absorptive capacity. People aspects highlight Communities of Practice, sticky knowledge, storytelling, cognitive maps and social network analysis. Structural and strategic aspects include exploration/exploitation, personalization/codification, alignment with business strategy and ba. Technological aspects feature ontologies. The chapter concludes that the main challenge for the future is to develop KM models that incorporate enough complexity to be effective, while remaining simple enough that people who are not KM experts can use them.