The average project that I record is done at this studio from start to finish. This typically includes tracking, editing, mixing and mastering. I am also available to do any of these things separately.
Mastering is a process that takes a finished mix and optimizes it to sound as good as possible on as many different playback systems as possible. It's the finishing touch on the recording process. Depending on the quality of the mix, mastering can mean anything from a lot of heavy processing to a simple seal of approval.
Also included in this step is sequencing (putting the songs in order and solidifying their transitions) and preparation for different mediums (vinyl, cd, tape, download, etc.).
Traditionally, records are mastered in studios that are built specifically for this purpose, and by engineers who specialize in this field. The Atomic Garden is not a mastering house, and I am not a mastering engineer. That being said, I am available to master recordings for a fraction of the cost of most mastering studios. And the quality is surprisingly similar.