Human history can be told in terms of the history of energy. The discovery of fire, the domestication of animals, the discovery of fossil fuels, the electrification of cities, and advances in nuclear physics all were pivot points in human history. Energy transitions are milestones in human history because they are accompanied by transformative cultural, economic, demographic, technological, and environmental changes. The transition to fossil fuel-based energy systems powered rapid economic growth and raised living standards, but it also caused pervasive environmental change at local, regional, and global scales, as well as violent conflict over remaining supplies of oil. The fossil fuel transition co-evolved with a culture that places a high value on consumerism and affluence, a lifestyle that requires large amounts of energy to support and generates significant wastes. Surging energy demand some developing nations, extreme energy poverty in others, and the need to manage future climate change are driving humanity to the brink of another major energy transition. The discussions at Energy in Context aim to bring a dispassionate and science-based perspective to these important issues.