This chapter introduces fundamental concepts about collections of interacting unities, providing a structured framework for understanding different types of organisational arrangements. It defines and distinguishes between systems, networks, and groups based on two key parameters: the regularity of interactions and Explicitly Agreed and Defined Objectives (EADOs). The chapter explores how collections can be viewed at different levels of abstraction, introducing the concepts of proximal and distant environments to contextualise boundaries and relationships. It presents two more distinct types of objectives that, together with EADOs, govern interactions within and between collections: Explicitly Expected and Trusted Objectives (EETOs), and Implicitly Assumed and Trusted Objectives (IATOs). The framework addresses how these objectives interact and transform, particularly in organisational settings, introducing the concept of Unsettled Side Objectives (USOs) to account for rejected or postponed objectives. Through practical examples ranging from workplace scenarios to public transport situations, the chapter demonstrates how these concepts apply in real-world contexts. This conceptual framework provides professionals with tools to better understand and analyse collective arrangements, their boundaries, and the various types of objectives that influence their interactions and outcomes.