This paper discusses the generic principles and technologies associated with Digital Twins that have been developing in the healthcare sector over the past decade. Various entities and processes in hospitals and clinics can benefit from having a direct digital counterpart. A digital twin allows for the design and optimization of medical devices within a digital environment. The adoption of Digital Twins in healthcare has accelerated, particularly for predictive maintenance. Digital Twins in healthcare leverage recent advancements in several other technologies, including the Internet of Things (IoT), the Internet of Medical Things (IoMT), artificial intelligence (AI), machine learning (ML), and augmented reality (AR), in ways that are specifically tailored to the healthcare field.