Physics with Calculus/Glossary
Closed systems are systems which do not interact with their environment. For example, if we are only considering the exchange of heat energy, the inside of an insulated box would be a closed system, since no heat can get in or out. Compare this with open systems.
Open systems are systems which interact with their environment, so that energy or mass can be added or removed from them. For example, a pot of water on a stove is an open system, because energy (in the form of heat) is added to the water by the stove. Compare this with closed systems.