A flow is information which enters, spreads through and leaves a system over a period of time. It can be realized in a system behavior as a discrete series of events over time. In graph theory, a flow network is a directed graph where each edge has a capacity and each edge receives a flow. In psychology, a flow is the mental state of operation in which a person in an activity is fully immersed in the process.
The flow of information is the fundamental force behind life, the universe, and everything. Information flows everywhere, through wires and networks, programs and applications, genes and cells, neurons and brains, animals and swarms, organizations and corporations, cultures and civilizations, and of course in societies of agents. The unified history of this flow is called evolution.