This chapter introduces e-government theory according to the development of information communication technology (ICT), in which the importance of national informatization has been emphasized and the goal of government has been converted to a new concept: that of e-government. First, we define several national concepts based on the study of those countries and international agencies with the most advanced structures of information society, and from these concepts, we establish the general concept from the viewpoints of supply, demand, and policy. Second, we explain how international agencies (UN, Brown University, Accenture, etc.) measure e-government according to the standards and performance. Third, we explain e-government projects that have been accepted as national policies under the national informatization plans and which have been executed in each country for better public service and efficient administration. Thus we expect that the countries needing a benchmark model while developing their own e-government may adopt the concepts we propose in this paper and may benefit from our experience to quickly embody e-government and evolve into the new paradigm that is mobile-Gov, TV-Gov, or ubiquitous-Gov.