Ontology is the philosophical study of being. It is concerned with everything that is real. Fundamentally, ontology deals with existence, identity, part, object, property, relation, fact and the world, building the framework for specification of conceptualization for a domain. Ontology, in this sense, provides the foundational principle for interpretation and conceptualization of multimedia content, which in a concrete form records everything perceivable through human senses and hence is linked to the reality of existence and the world. The representation for a concept is to be constructed through a hierarchy of descriptors and linguistic references built upon raw multimedia data. Standardization of the descriptor set as attempted in MPEG-7 provides the basic terminological layer for describing multimedia content. Ontological layers have been constructed on top of these standardized descriptors. In this chapter, we examine these representations. We also identify basic conceptual problems with these approaches.