An isolated system is a physical system that does not exchange matter or energy with its surroundings. This means that the total energy and mass within the system remain constant over time. An example of an isolated system is a perfectly sealed container in space, where no heat or particles can enter or leave. In thermodynamics, isolated systems are important for understanding the principles of energy conservation and entropy. They help scientists study how systems evolve without external influences. The concept is often contrasted with open and closed systems, which do interact with their environment in various ways.