In the digital world today, data is not just a valuable resource—it is the backbone of innovation, strategic planning, and operational effectiveness. But data’s true potential is not realized when it exists in silos in separate systems with diverse standards and protocols. Data interoperability—being able to share, interpret, and utilize data freely—is the driver to turn isolated data into a strategic resource. This chapter delves into data interoperability’s fundamental definitions, root principles, and development. It discusses technical, semantic, and regulatory obstacles organizations encounter, identifies best practices and solutions for overcoming such obstacles, and demonstrates real-world implementations across health care, finance, and smart cities. The chapter also explores emerging topics like AI-powered integration, blockchain, and quantum computing and offers imperative views on security and compliance issues. Descriptive mind maps and comprehensive tables are provided to facilitate understanding, and a comprehensive reference list guides readers to seminal and contemporary contributions in the area.