Heterogeneity and a lack of central control over the organization of Web information have led to great difficulties in processing them automatically. To overcome the difficulties, one attempts to add meta-data to Web pages and this is known as Web Annotation. Ontology-based Heterogeneity and a lack of central control over the organization of Web information have led to great difficulties in processing them automatically. To overcome the difficulties, one attempts to add meta-data to Web pages and this is known as Web Annotation. Ontology-based Web Annotation is a recent but promising area which enhances conventional Web Annotations by incorporating ontology with pre-defined semantic structures. The resulting annotations are useful not only for navigating Web information from diverse sources but also for improving information retrieval and classification. In this paper, we survey the different Ontology-based Web annotation methods in order to provide an organized view on the existing state-of-the-art, to identify potential areas of research, and to discuss promising ways of enhancing Ontology-based Web Annotation.semantic structures. The resulting annotations are useful not only for navigating Web information from diverse sources but also for improving information retrieval and classification. In this paper, we survey the dif- ferent Ontology-based Web annotation methods in order to provide an organized view on the existing state-of-the-art, to identify potential areas of research, and to discuss promising ways of enhancing Ontology-based Web Annotation.