Musical ontology answers the questions regarding the categorization of musical works and aims to explicate sorts of realtions that musical works have with their manifestations. Musical work has to be understood as a separate entity in a relation to its manifestations (performances, sound tracks), so the question of the true nature of musical works arises. Musical ontology theories mostly follow contemporary general ontology theories, so this work deals with theories of musical idealism, musical platonism, theory of historic individual and so on. Second part of this work analyses characteristics of musical manifestations and aims to detect forms of music that we encounter in the world of today, with the overview of the historic changes caused by the emergance of musical production and reception technologies, from gramophones to streaming services. This work is conceptualized as a review work which shows contemporary musical ontology theories and analyses the questions that appear after a philosophical deliberation about the phenomena of a musical work.