Personalized E-learning resources are of great importance for every adaptive or intelligent tutoring system. In this paper we will discuss the role of semantic models for development of personalized e-learning content. We systematize the main concepts, needed for overall description of all components of the learning process and their relationships and propose a ontology, modelling general knowledge in all the sub-domains of e-learning domain and its important relationships. This ontology will be most useful for annotation of the learning objects to support personalized tutoring.