Public Data Networks provide a comprehensive survey of PDNs, covering all major countries. PDNs allow efficient and cost-effective telecommunication between a terminal and computer, or between computers, regardless of who owns the data terminal. The authors discuss the current state of, and forthcoming developments in, data communications using public telecommunication facilities. Apart from the classical telecommunication networks (telegraph and telephone), public data networks provide the majority of data communication services worldwide. The range of data services and user facilities has gradually expanded, the quality of services improved, and new services have appeared (e.g. datafax, teletex, videotex, message handling and teleconferencing). The authors concentrate on PDN principles, taking account of the latest CCITT recommendations and ISO standards. Appendices and references provide detailed information for those working on PDNs at research, design an implementation level. Network digitalization and integration of networks and services have aided progress towards the integrated services digital network (ISDN). The ISDN uses advanced transmission and switching techniques to enhance the telecommunication services provided to its users. An ISDN has much in common with the PDN as far as architecture, methods of network management and functions are concerned, but there are distinct differences in the methods of access and signalling. The authors have extensive experience in data communication networking. Dr. Kubin is vice-chairman of Study Group IX of the International Telegraph and Telephone Consultative Committee (CCITT); Dr. Puzman is the Czechoslovak representative at Technical Commission 6 (TC-6) of the International Federation for Information Processing (IFIP). Public Data Networks is essential reading for researchers and designers of PDNs, in universities and industry, and provides important reference material for telecommunications and computer science students.