This chapter provides a basic understanding of modular construction and its increasing importance in contemporary project delivery by introducing the idea of modularity methodology within the framework of the construction industry. Buildings that are constructed off-site, under controlled plant conditions, with the same materials and designed in accordance with the same codes and standards as conventionally built facilities, but in roughly half the time, are referred to as modular construction. Because of its potential to shorten construction times, cut waste, improve quality control, and increase safety, this strategy is becoming increasingly popular. The chapter opens with a summary of the global issues that call for more economical, sustainable, and efficient building techniques, presenting modular construction as a workable answer. The problem statement highlights the shortcomings of conventional building techniques in meeting modern demands like project delays, labour shortages, urbanisation, and environmental concerns. The chapter defines modular construction and explains its basic concepts, including prefabrication, standardisation, and off-site production. A historical overview traces the development of modular building from its first applications in post-war housing to its current applications in commercial, residential, and infrastructure projects. The book aims to provide comprehensive insights into modular construction techniques, their benefits, drawbacks, and the factors influencing their adoption in different geographic areas. The chapter also summarises the book’s primary objectives and contributions. Additionally, it discusses how modularity in construction promotes technological innovation, sustainability, and productivity. The book’s format serves as a roadmap for the reader as they progress through the following chapters, which cover case studies, theoretical frameworks, best practices, and new trends.