Mastering, a form of audio post-production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device (the master) -the source from which all copies will be pressed, duplicated or replicated.

Measurements are completed to determine the current state of the mix so that, typically, the mastering engineer can apply shine, polish, punch, depth and definition to the stereo image and overall clarity to the track. Corrective equalization and dynamic enhancement may also be applied in order to improve upon sound translation on ALL playback systems (very important). While these are subjective terms, the art of the procedure involves critical listening in order to make objective and scientific decisions about the sound quality. Therefore it can not be achieved without the presence of a mastering engineer (an actual human being).

The mastering process continues to resist automation. There are software tools available to facilitate this but results still depend upon the accuracy of speaker monitors, and also critical, completing the work in an acoustically calibrated environment.