A survey on the state of the art in Dielectric Waveguide (DW), stressing in particular the practical microwave applications, is given. The principles for designing DWs, fixing and joining devices, launchers, various multiport networks etc. are founded. A simple theory to calculate parameters of multiport networks with distributed coupling is developped. Some microwave technique problem, which it is reasonable to solve making use of DWs, are discussed. Some advice on the frequency range and materials applied is given. Pictures and photographs of the DWs and the devices designed will be presented. This paper is an attempt to give a survey on the state of the art in Dielectric Waveguide (DW), stressing in particular the practical microwave applications.