One of the main concerns of mankind nowadays is the proper generation and storage of energy as this matter became the support for the proper functioning of any other technology. Alongside that, the implications for finding alternative energy sources increase the pressure for the development of novel materials that can simultaneously generate or store energy sustainably and efficiently. For that, understanding the main technologies present in society along with the core materials that can serve as components is a highly regarded knowledge. Based on these aspects, this book chapter focuses on providing a diverse yet precise discussion regarding the main technologies related to energy such as supercapacitors, batteries, photovoltaic cells, fuel cells, electrolyzers, and piezo and thermoelectric devices. Also, to further address this topic the final session of the chapter is devoted to the most research electroactive materials that are employed in these technologies. This discussion is backed by the most recent literature work to provide the main concepts as well as encourage the readers to obtain novel ideas related to the vast field of materials suitable for energy applications such as carbon-based nanomaterials, MXenes, transition metal oxides, sulfides, phosphides, Si-based nanomaterials, and its respective composites.