The term diagnostics is often understood as a set of actions aimed at detecting hidden defects, resulting in faults or deviations from the design mode of the object as a whole or its individual parts.

The concept of diagnostics of machines, units and constructions also relates to the terms monitoring and prognosis. Monitoring is a process within which the overall control of the system is conducted. Prognosis (forecasting) refers to an informed judgment about the possible condition of the object in the future in order to optimize the planning of its operation. In order to forecast, it is necessary to know the condition of the object, which is developed on the basis of monitoring and diagnostics results.