Thermal equilibrium is a state in which two or more objects in contact with each other reach the same temperature, resulting in no net heat transfer between them. This occurs when the energy lost by the hotter object equals the energy gained by the cooler object, leading to a stable condition. In practical terms, when a hot cup of coffee is left on a table, it will eventually cool down to room temperature while the table warms slightly. At this point, both the coffee and the table are in thermal equilibrium, as they share the same temperature and no heat flows between them.