This course covers a range of important topics in modern data communications. We start with introduction of multimedia communications where different types of media such as text, image, audio and video are generated and being transferred over networking infrastructures. Multimedia applications pose new challenges to data communications, i.e. requirement of quality of service support. The new development in the Internet technologies is described to illustrate how to meet these challenges. The course also discusses a selection of topics which related to recent trends in data communications: network security and network management.