A grand variety of ontologies have been developed and tested in e-learning projects recently. One of the main purposes of the most projects is knowledge reuse, but only few ontologies are used or reused in practical e-learning systems. In this monograph, we comprehensively survey the usage of ontologies in e-learning, analyze the role, current state and outline the future of ontologies related to E-Learning. We discuss how ontologies should be used in practical e-learning systems to achieve improvement of the e-learning process at the acceptable cost. We also analyze specifics of the...