The viable system model (VSM) is a model of the organizational structure of any autonomous system capable of producing itself. A viable system is any system organised in such a way as to meet the demands of surviving in the changing environment. One of the prime features of systems that survive is that they are adaptable. The VSM expresses a model for a viable system, which is an abstracted cybernetic (regulation theory) description that is claimed to be applicable to any organisation that is a viable system and capable of autonomy. Overview The model was developed by operations research theorist and cybernetician Stafford Beer in his book Brain of the Firm (1972). Together with Beer's earlier works on cybernetics applied to management, this book effectively founded management cybernetics. The first thing to note about the cybernetic theory of organizations encapsulated in the VSM is that viable systems are recursive; viable systems contain viable systems that can be modeled using an identical cybernetic description as the higher (and lower) level systems in the containment hierarchy (Beer expresses this property of viable systems as cybernetic isomorphism). A development of this model has originated the theoretical proposal called viable systems approach. Components Here we give a brief introduction to the cybernetic description of the organization encapsulated in a single level of the VSM. A viable system is composed of five interacting subsystems which may be mapped onto aspects of organizational structure. In broad terms Systems 1–3. are concerned with the 'here and now' of the organization's operations, System 4 is concerned with the 'there and then' – strategical responses to the effects of external, environmental and future demands on the organization. System 5 is concerned with balancing the 'here and now' and the 'there and then' to give policy directives which maintain the organization as a viable entity. System 1 in a viable system contains several primary activities. Each System 1 primary activity is itself a viable system due to the recursive nature of systems as described above. These are concerned with performing a function that implements at least part of the key transformation of the organization. System 2 represents the information channels and bodies that allow the primary activities in System 1 to communicate between each other and which allow System 3 to monitor and co-ordinate the activities within System 1. Represents the scheduling function of shared resources to be used by