Mixing with COMPRESSION

Compression is the process of shaping the dynamics of sounds. A compressor is an automated volume control. It automatically adjusts the volume of the input signal in response to changes in volume in the signal itself.
 
Compressors are difficult to learn to use, for several reasons. They have many different and unrelated purposes. They have complex mechanics of operation, and it is necessary to understand these mechanics in order to operate them. Their effect on the sound is not always readily audible. And finally, the specific things that one has to do to get good results out of them are routinely very different from what one would intuitively expect.