What is digital health, eHealth, uHealth and Healthcare 4.0?

As digital health continues to evolve, the need for ongoing refinement of its terminology remains essential. A perspective piece originated from the authors' attempt to answer the seemingly simple question, "What is digital health?" Defining the term proved unexpectedly challenging, as a review of the literature revealed numerous scholars highlighting the difficulty of establishing clear and consistent definitions. After examining past research where digital health has been defined, this perspective piece provides a revised definition that integrates key related concepts, including eHealth, uHealth, mHealth, and Healthcare 4.0. A contemporary framework for understanding digital health is proposed through understanding four key subdomains: (1) how healthcare is delivered through eHealth which includes mHealth, telehealth, and uHealth; (2) how digital health products are regulated which includes digital wellness and therapeutic solutions; (3) how society, industry, and clinical care are impacted which can be understood through the lens of Healthcare 4.0; and (4) how data is utilized through health informatics. • Despite the rapid expansion of digital health, a lack of consensus on terminology remains. • Digital health as a term includes considering healthcare delivery through technology, product regulation, societal impact, and data use. • eHealth is an umbrella term including computer-based, mobile (mHealth), remote (telehealth), and anytime and anywhere health through Ubiquitous health (uHealth).