Open system and Close system

Close system

In thermodynamics, a closed system can exchange energy (as heat or work) but not matter, with its surroundings.
A closed system is one in which no mass crosses the system boundaries, but energy can cross the system boundary in form of heat and work.

Open-Close-Isolated System

Open system

An open system can exchange all heat, work and matter, with its surroundings.
An open system is one in which mass crosses the system boundaries. The system may gain or lose mass or simply have some mass pass through it.

See also Isolated system.