In this chapter provides an overview and histories of Digital Transformation and Enterprise Architecture, the purpose, scope and structure of this book. This chapter covers the primary previous researches regarding Enterprise Architecture, consisting of main four categories as well. During 1980s, the term of Architecture Framework appeared with the publication of the Zachman Framework for Information System Architecture. Since the year 2000, Enterprise Architecture has been focused as a method for promoting an IT architecture that establishes consistency between corporate business and IT strategies, and it has been applied mostly in global corporations. And whereas, with the recent progress in cloud computing, Mobile IT technology and big data solutions, in the IT systems of global corporations, the shift from conventional on-premise server-based IT systems to cloud computing, such as Software as a Service (SaaS), hybrid cloud and connected mobile IT systems, has become more pronounced. This book focuses on Architecture Framework suiting an era of digital IT. In later chapters, we will show the direction of digital IT, involving AI, and Enterprise Architecture, Strategic Architecture framework suiting in a digital IT era.