Renewable energy (RE) technologies' market is on the rise, and the world is witnessing a new energy transition with many factors and drivers pushing it. To properly understand this phenomenon, it is vital to apprehend the correlation between the development of economies and the different energy transitions through history. It is also important to understand the rationale behind the current transition to renewables and their economy; this book presents and discusses both points. The histories of energy transitions, development of economies and industrial civilizations, all go hand in hand. Going back in time, people only needed to cover their basic needs, such as food, which -at the very beginning- was met by using firewood for cooking and heating. Further in time, people star-ted practicing agriculture in the first formed human communities, essentially depending on the sun for that practice, in combination with biomass. As economies evolved and developed into complex forms, firewood and other biomass were no longer able to meet the increasing demand in energy. So, people started turning into hydropower, then to coal during the 19th century.