This chapter introduces the concept of domain engineering and explains how it can be applied to healthcare systems to create reusable, adaptable, and scalable components. Domain Engineering is broken into three phases: Domain Analysis, Domain Design, and Domain Implementation. These phases enable organizations to identify commonalities within systems, design reusable architectures, and implement those architectures for large-scale use. The chapter also explores the use case of implementing Global EHR systems using domain engineering techniques. It highlights how blockchain technology can improve EHR systems’ security and privacy by ensuring decentralized, immutable, and encrypted data storage. Finally, the chapter discusses the challenges of adopting blockchain technology in healthcare systems, including scalability, interoperability, and regulatory compliance.