A thermodynamic operation is an externally imposed manipulation or change of connection or wall between a thermodynamic system and its surroundings. An externally imposed change in the state of the surroundings of a system can usually be regarded as a virtual thermodynamic operation. It may usually be analyzed as due to changes in the walls that separate the systems in the surroundings. It is assumed in thermodynamics that the operation is conducted in ignorance of any pertinent microscopic information.