A thermodynamic operation refers to any external manipulation impacting a thermodynamic system. This can involve alterations to the system's boundary with its surroundings or changes in the values of variables within those surroundings that interact with the system's boundary, facilitating the transfer of extensive quantities associated with those variables. In thermodynamics, it is assumed that such operations occur without consideration of relevant microscopic details.
A thermodynamic operation requires a contribution from an independent external agency, that does not come from the passive properties of the systems. Perhaps the first expression of the distinction between a thermodynamic operation and a thermodynamic process is in Kelvin's statement of the second law of thermodynamics: "It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the surrounding objects." A sequence of events that occurred other than "by means of inanimate material agency" would entail an action by an animate agency, or at least an independent external agency. Such an agency could impose some thermodynamic operations. For example, those operations might create a heat pump, which of course would comply with the second law. A Maxwell's demon conducts an extremely idealized and naturally unrealizable kind of thermodynamic operation.