SIDECHAINING is a very powerfull technic to improve the dynamics of a track. its nothing else as a inversed GATE, which means that some element drops away when another is being played. You can use sidechaining for very different results, but the most famous one is sidechaining the bass with the kick, means the bass will go off, when the bassdrum hits. The results are very organic and warm in my opinion, reading this tutorial will help you to understand SC and to transform this knowlegde into other applications.