==> Crashkurs Systemtheorie

Stock and Flow ist ein Begriff aus der System Dynamics, der ein zentrales Konzept focusiert. Stock and Flow stehen für zwei Variablen-Typen, in der Systemmodulation, die hauptsächlich Trägheit von In-Out-Put-Systemen behandelt. Dynamik wird dabei gesehen als Flüsse, die in Speichern (stocks) akkumulieren.

Beispiele:
WC-Spülkasten, Portemonnaie, Bankkonto

Economics, business, accounting, and related fields often distinguish between quantities that are stocks and those that are flows. These differ in their units of measurement. A stock variable is measured at one specific time, and represents a quantity existing at that point in time (say, December 31, 2004), which may have accumulated in the past. A flow variable is measured over an interval of time. Therefore a flow would be measured per unit of time (say a year). Flow is roughly analogous to rate or speed in this sense.
Quelle: Wikipedia