Liquid chromatography (LC) and mass spectrometry (MS) are transformative analytical techniques that have revolutionized clinical diagnostics by enabling highly sensitive and specific detection of various essential analytes and compounds in clinical samples. Successfully adopting this technology in clinical laboratories is a complex process that requires years of expertise and dedicated effort. This book was created to share collective experience and provide practical guidance for implementing LC-MS/MS in clinical laboratories. This chapter serves as an introduction to the book, exploring the historical development, current applications, and future potential of LC-MS/MS in laboratory medicine. It also outlines the overall design of the book, detailing the focus of each chapter and its interconnections. By providing essential background and a comprehensive overview, this chapter aims to equip readers with the foundational knowledge needed to navigate the book effectively. We hope this chapter bridges historical insights with practical strategies, enabling readers to optimize the use of LC-MS/MS in their clinical laboratories. Our goal is to empower laboratory professionals to implement this powerful platform efficiently and confidently, ultimately advancing patient care.