Abstract: The idea of the semantic web is to add machine process able information to web-based data in order to realize interoperability. Ontology is a shared conceptualization of knowledge representation of particular domain. These are used for the enhancement of semantic information explicitly. Ontologies play a prominent role in the concept of the semantic web to provide semantic information for assisting communication among heterogeneous information repositories. Ontology interoperability provides the reusability of ontologies Different domain experts and ontology engineers create different ontologies for the same or similar domain depending on their data modelling requirements. These cause ontology heterogeneity and inconsistency problems. As increasing numbers of ontologies are developed by diverse communities, the demand for rapid ontology mapping is arising. For more better and precise results ontology mapping is the solution. As their use has increased, providing means of resolving semantic differences has also become very important. Studies on ontology interoperability report the results on different frameworks and this makes their comparison almost impossible. Therefore, the main focus of this study will be on providing some basics of ontology interoperability and briefly introducing its different approaches. In this study, researchers survey the approaches that have been proposed for providing interoperability among domain ontologies and its related techniques and tools.