Mastering is the final stage of audio production before a recording is distributed. The mastering engineer works with the mixed stereo (or surround) file, making subtle adjustments to overall level, equalization, stereo balance, and dynamic range so the music translates well across different playback systems.

The process also includes sequencing the tracks for an album, setting appropriate gaps, and ensuring consistency of loudness and tone from song to song. Technical standards for various delivery formats—streaming, CD, vinyl—are applied at this stage.

Good mastering is often invisible; listeners simply experience a polished, competitive sound. Poor mastering can leave a mix sounding dull, harsh, or uneven. Because the changes are usually small, the engineer relies on high-quality monitoring and experienced ears. Mastering is distinct from mixing, which balances the individual tracks that make up the recording.

The finished master becomes the source for all subsequent copies.