What is a mastering?
It is the “art and science” of assembling songs into a cohesive ensemble.
The audio mastering is the last step before releasing your music; it ensures that the material is optimized for its final medium (digital, CD, vinyl, tape…)
A mastering session includes:
- Bit/sample rate conversion (if required)
- Noise reduction
- Equalization
- Stereo width adjustments
- Dynamic compression or expansion, loudening
- Track ordering
- Spacing (pause between tracks)
- Fades in/out, crossfades
- Levels (volume adjustment)
- PQ codes
Also: Removing clicks, pops, hisses, or any interfering noise, doing some edits (to remove, add, mix, or rearrange some parts of the tracks), adding effects (reverb…)
See the Audio Mastering entry on Wikipedia for additional information.