What is mastering?

Mastering is the process of readying finished audio tracks for cd replication. The goal of mastering is twofold:

The first is to make all of the tracks similar in tone (eq) and level. Typically music nowadays is recorded at multiple locations over a range of time utilizing varied pieces of equipment. By applying eq, compression, and limiting to each track individually, these differences can be minimized.

The second is to make your tracks sound as good as possible on a wide range of listening devices (i.e. personal stereo, boom box, car, and home. A good sounding cd is one that sounds good on many different types and size of speakers.