Mastering is the final step in the creative production process. Mastering is not meant as a complete overhaul of your mix. It is there to enhance or finalize your mix. Mastering is also a means to prepare your mix or mixes for final delivery. Which could be CD, MP3, AAC, Wave Files, FLAC, Digital Streaming, Vinyl, and more.
In mastering we utilize many tools. Equalization, Compression, Stereo Enhancement, Harmonics, Saturation, Limiting, and more. You can see many of the tools we use at Studio M Mastering on the gear page.
One of the reasons to have your project mastered is to have some fresh ears on your music. At Studio M Mastering one of the first things we do is just listen to your mix. We listen differently than you would during the mix session. In mixing you are focused on the individual instruments. In Mastering we are macro listening. Listening for anomalies, listening for uniqueness, listening to your mix and it's blend, and overall tonal balance. We are also listening to how each song flows from one to another. Do they have similarities? Mainly we are devising strategies to make your mixes translate with maximum impact. All this takes place before any actual processing is done.