This is where the magic happens.

And by "magic", I mean the hard work and specialized knowledge that can take you from an unfocused, dull, washy, mushy, mess to a vibrant piece of art with clarity, purpose, and power.

This can include, but is not limited to:

EQ, Compression, Parallel Compression, Limiting, Normalization, Saturation, Automation, Delay, Reverb, Creating Busses and Sends, Balancing Levels, Magical Incantations, Etc.