This article reviews the novel technology named nanophotonics, which is an innovative technology utilizing the local energy transfer between nanometric materials induced by optical near fields. As an introduction to other review articles in this issue, history of this technology, theoretical picture of optical near fields, and examples of technical developments are surveyed. Among a variety of applications, progresses in developing devices, fabrications, system applications, and energy conversions are introduced. Recent status of research and development in US and EU, cooperation between industry and academia, and future outlook are also described.