This study presents a comprehensive overview of the digital twin concept with a specific focus on its applications in the wind energy industry. In civil engineering, the concept and development of a digital twin is increasingly being explored. They show significant potential in almost all life cycle phases, including design, construction, operation, maintenance, and demolition. However, the exact function and implementation of digital twins lack a clear definition and continue to be the subject of research. This paper investigates the
implementation and recent developments of digital twins with respect to the life cycle phases, the maturity level, the hierarchy level, and the used source of information of wind turbines. To achieve this, a systematic literature review of published papers was first performed, including papers related to digital twins in the field of wind energy science. As a result, 27 research papers were found. Secondly, the concepts, methods, and application cases of the targeted papers were summarized and analyzed. Then, the application of a digital twin of an offshore mega structure is presented as a case study, which is developed within the basic research project of the Collaborative Research Center 1463. Finally, a discussion on the implementation of digital twins in the life-time comprehensive digitization of wind turbines is given.