Compression in the most simple terms is automatic volume control. Despite this essential simplicity, there is much more to compressors and their uses than basic level control. There are many nuances and variations between compressor models and the resulting sounds that they can offer to your production palette. Differences in how the gain reduction is achieved such as feedback, feedforward, VCA, tube or variMU can significantly shape the nature of the punch, texture, movement and sounds that these devices can create. Given the depth and breadth of these variations, compressors have many uses in many audio contexts.

Compressor plugins can be used to: 

• Control volume, to help maintain a consistent volume of a track, to bring low level audio that would otherwise get lost in a mix higher.
  
• Hold and maintain unwavering focus on a track, vocal or instrument.
  
• Shape the volume envelope by adding or removing attack, decay or punch.
  
• Change the groove or pulse of a track by changing the contour, enveloope or accents in the music.
  
• Dynamically change the frequency distribution of the audio being compressed, by frequency selective gain reduction or eq’d or filtered sidechain detection.
  
• Create or add texture to sound with extremely fast attack and release times that shape or distort the actual wave form.
  
• Add harmonics, saturation or distortion via the circutry of the line amps, input and output tranformers (often without any gain reduction).
  
• Alter the overall sound as many compressors are often just used for their “box tone” without any gain reduction.
  
• Increase the preceived density of a track
  
• Perfornm simple gain control.
  
• Duck or surpress sounds in response to the volume and presence of others.
  

As you can see, in real world use, compression is effectively much more than just audio gain control. With the plethora of compressors plugins that exist on the market today, we will explore, review and listen to discover their strengths, weaknesses, quirks and peculiarities that can add to your music and audio productions.