"A concrete system with impermeable boundaries through which no matter-energy or information transmissions of any sort can occur is a closed system. This is a special case, in which inputs and outputs are zero, of the general case of open systems. No actual concrete system is completely closed, so concrete systems are either relatively open or relatively closed. In closed systems, entropy generally increases, exceptions being when certain reversible processes are carried on which do not increase it. It can never decrease."

Slots and Values
source	Unnamed