From the discovery of fire to that of the atom, the development of human societies has largely been based on the conquest of energy. In all countries, energy has gradually become one of the key factors of social and economic development, as well as capital, labor and natural resources, and now no one can do without it. After decades of cheap energy flowing without any problem, over the last forty years crises have become the rule. This disruption of the energy landscape is of particular concern as the impact of energy crises on human societies became considerable. This book seeks to provide a basis for reflection on all global energy problems, offering an analysis of the main aspects to consider: energy supply, resource-dependent industries and technology available, macroeconomic implications of energy demand, geopolitical issues, and specifics of the situation in developing countries. It does not thoroughly address environmental issues, which would require further study beyond the limits we set. This book is the second edition of a book published in 1992, at a time when obtaining energy and economic data was much more difficult than today, when many databases are freely accessible on the Internet. In this new context, we hope it will assist the reader in finding his/her way in the considerable amount of information available. Energy is a vast field that can be approached from multiple angles. The approach proposed here is to start by providing the reader with technical bases on energy, and thus energy supply, before considering the demand, that is to say, the socio- and macro-economic dimensions, then addressing global issues relating to energy, and finally complete the study of the main issues that arise in this area today. This book summarizes the main issues related to energy and requires no special knowledge beforehand, whether in economics, engineering or international relations. It consists of nine chapters, the first being the introduction. Chapter 2 introduces the main energy sectors (oil, natural gas, coal, synthetic hydrocarbons, nuclear power, renewable energy, thermal or pneumatic storage), i.e. how the main sources of energy can be exploited. Chapter 3 presents the main macroeconomic and energy indicators that are commonly used to assess the energy situation in a country. Concepts that are introduced being then used consistently in other chapters, it is essential to understand well their definitions and limitations. The fourth chapter analyzes the impacts of energy at the macro level, including the links between economic activity and energy consumption. The fifth chapter introduces the main principles generally accepted in the development of energy policy and planning, and then discusses the institutional aspects. The sixth chapter is devoted to geopolitics: current consumption of energy, energy reserves and resources worldwide, international energy trade, and specific problems faced by developing countries. The seventh chapter is devoted to the study of the energy situation in eleven different countries, showing the contrast between them, depending on their level of economic development, demography, natural resource endowments, etc. The list of countries includes high-income developed countries (France, United States, United Kingdom), the emerging group called the BRICS (Brazil, Russia, India, China, South Africa), a North African oil exporting country (Algeria), a west African country (C�te d'Ivoire), and an Asian exporter of coal and natural gas (Indonesia). The eighth chapter discusses emerging issues related to energy, in particular its relationship to the environment and the success of policies aiming at controlling demand. The ninth and final chapter begins with a prospective study of various scenarios for the medium and long term. The analyses presented in the book are then summarized by outlining the main pending issues. The book includes 22 tables, 150 figures and 3 mind maps, as well as links to databases available online (World Bank, United Nations, BP). Also available: an online course covering the main topics dealt with in this book. Please visit: http://www.thermoptim.org/sections/enseignement/cours-en-ligne/modules-d-auto-formation/energy-issues-course.