This latest Topic in Depth delves in the Web's offerings on the history of energy. The first site is maintained by the US Department of Energy, which is called Milestones in the History of Energy and Its Uses (1). From fire to the discovery of nuclear energy, the site gives short descriptions on significant events in the history of energy for each century, events by particular fuel type, events by energy uses, how energy uses have changed, energy consumption changes, and more. The next site entitled Botticelli's Famous History of Energy Timeline (2) is provided by the Association for the Promotion and Advancement of Science Education. Visitors, especially kids, should enjoy the simple and brief explanations on energy discoveries and uses from ancient times until the 1900s, along with the additional links on coal and petroleum. One specific segment of the energy industry is offshore oil and gas exploration. The National Ocean Industries Association's Web site explores this topic on its History of Offshore (3) page. The site describes how this technique started, how it has evolved, and how it's been regulated. The fourth page, Hydropower (4), is part of a Massachusetts Institute of Technology course Web site. Water power is explored from the origin of the waterwheel around 100 BC to large hydroelectric dams of today. Although graphics are not used extensively, the easily read narrative and provided links give a good introduction to the topic. The next site, from TelosNet, is called the Illustrated History of Wind Power Development (5). The contents include a case for wind power use, its early history, 20th century developments, the future of wind power, and more. From Energy Quest of the California Energy Commission, the Energy Time Machine (6) Web site gives an extensive look at the history of energy. Users choose from dozens of specific eras to locate and discover educational tidbits such as, in 1814, when the first American steam-powered warship was launched. The seventh site, brought to the Web by Dias-Analytic, is called the History, Theory and Operation Of Fuel Cells (7). Described is the background and history of how fuels (hydrogen and oxygen) produce electrical energy by means of a chemical reaction. The last site explains the history of solar energy. As part of the High Altitude Observatory Web site, the Solar Physics Information (8) page tells visitors the history of solar physics, including great moments in its history, how the sun works, what a sunspot is, and other interesting topics worth exploring.