This chapter presents a brief history of the emergence of the domain of human resources management (HRM) followed by how its context, approach to thinking, and practices have been influenced by the four industrial revolutions. This is followed by some of the core language and concepts used when discussing social and organizational systems and organizational complexity. As many of these concepts do not have shared meaning and may vary across professions and practices, they may not be familiar to many of those who work in organizations or who practice professionally as human resource management (HRM) leaders and managers.