The main message that we were keen to convey in this part was as follows. Whatever the nature of self-sustained oscillations we are faced with, be it perfectly periodic, deterministically chaotic, influenced by noise or even noise-induced, and no matter what the exact form of coupling between them is, they all obey the same laws dictated by the fundamental and universal phenomenon of synchronization. There are three mechanisms of synchronization: phase (frequency) locking, suppression of natural dynamics, and crisis, or homoclinic bifurcation.