Energy, including energy supply and consumption, along with their security, represent one of the most important topics of today. What kind of energy resources can be used in what way to satisfy the ever growing energy demands of the population? How does meeting energy demands affect the environment? This presentation introduces the basic terms related to energy - such as work, heat, energy and capacity - very often misused in everyday speech. We also become acquainted with the history of energy consumption in Hungary, and after looking at the current usage, we examine the role of traditional and renewable energy sources in order to arrive at the potential energy sources and new energy technologies of the future.