The aim of this introductory chapter is to provide a description of the evolving operating landscape of safety-critical systems (e.g. aviation, chemical and nuclear industries, railway) in the past two to three decades, towards network config- urations based on contracting out. The topic of this book is strongly connected to this evolution and our understanding of its consequences for safety. The chapter situates the rise of these network configurations in the context of the advent of what has been described as globalisation, a phenomenon shaped by the liberalisation of trade and finance; privatisation and deregulation and the development of technology (commu- nication, transport). A distinction between occupational safety and process safety is introduced to remain aware of different situations, depending on their nature, and positions within such networks. The chapter then summarises the different contribu- tions to this book by a range of authors who bring unique lenses to this topic from a diversity of angles.