This overview will describe briefly key segments of the hydrogen energy cycle from production using various feedstocks to its end use in fuel cells to generate electrical and thermal energy. The paper will also discuss the larger societal context, the so-called “hydrogen economy,” in which such production and use of hydrogen may take place. Although most of the public attention on hydrogen has been focused on its potential as an alternative energy source to petroleum and other fossil fuels, a hydrogen economy will encompass much more than a substitution of one energy source by another. Widespread use of hydrogen as an energy carrier can transform our society in much the same way that personal computing technologies have. This transforming power arises from the unique capability of hydrogen to link renewable energy resources and zero-emission energy conversion technologies. Hydrogen can be produced from locally available renewable resources, such as solar, wind, biomass, and water, and converted to electricity or fuel at or near the point of use with only heat and water vapor as “emissions.” Hydrogen also lies at the confluence of two emerging trends that will shape our energy future during the first quarter of this century: greater reliance on renewable energy sources and the shift from large, centralized power plants to smaller, decentralized facilities located at or near the point of use. This paper describes these emerging trends and the role of hydrogen in linking them in a way that could transform our society.