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 balance in thermal energy. In practical terms, when you place a hot cup of coffee on a table, the heat from the coffee will transfer to the table until both reach the same temperature. At this point, the coffee and the table are in thermal equilibrium, and they will no longer exchange heat.