How does heat transfer occur between objects of different temperatures, such as when cold goes to hot?

Heat transfer occurs between objects of different temperatures through the process of conduction, convection, or radiation. In the case of cold going to hot, heat is transferred from the colder object to the hotter object until they reach thermal equilibrium. This transfer of heat occurs because heat naturally flows from areas of higher temperature to areas of lower temperature in an attempt to balance out the temperature difference.