In Computer Science and Information Science, Ontology is a formal representation of knowledge as a set of concepts within a domain, and the relationships between those concepts. Ontology is the basics of knowledge representation and automated reasoning in computer systems. The theory of ontology can be applied as the method of knowledge representation and automated reasoning in the fields of Artificial Intelligence, System Engineering, Software Engineering, Bioinformatics, and Library Science. This course, taking the Semantic Web as an example, introduce and discuss the state-of-the-art theories, methods, and frontier technologies about the information representation and data management, knowledge representation and ontology languages and their querying and reasoning on the current Web.