Global energy use has grown with the advance of human civilization such that we now use approximately 175,000 TWh of energy per year. This demand for energy provides essential services, from lighting homes to producing heat for industrial processes. Human demand for energy in the coming decades is highly uncertain. Climate change, the consequent necessity for decarbonization, and the many possible technology and policy pathways to net zero emissions (or not) mean there are many possible futures for energy demand. Regardless of this uncertainty, change in the energy sector is happening already, with greater change to come. In this article we discuss fuels and energy carriers, energy sectors and end uses, emerging energy vectors and new technologies, and lastly the cross linking of energy sectors and vectors.