Stocks and Flows

In system analysis, A stock is the foundation of any system. Stocks are the elements of the system that you can see, feel, count, or measure at any given time. A system stock is just what it sounds like: a store, a quantity, an accumulation of material or information that has built up over time

A stock is the memory of the history of changing flows within the system.

Stocks change over time through the actions of a flow.

If you understand the dynamics of stocks and flows—their behavior over time—you understand a good deal about the behavior of complex systems

A stock can be increased by decreasing its outflow rate as well as by increasing its inflow rate.