Closed system

An open system can be influenced by events outside of the declared boundaries of a system. A closed system is self-contained: outside events can have no influence upon the system. In practice many things are a mixture of the two. For example a prison is a closed system because the prisoners can't get out, and the wardens spend most of their time at the prison. However it is also an open system, because it depends on outside factors and the prisoners and wardens do go outside. Dynamic systems have components or flows or both, that change over time.