The main focus of the thesis entitled Registers and Passaggi of the Vocal Voice is to analyze in detail all the registers of the human voice in order to achieve vocal unity. This is a complex topic that is particularly important for opera singers, so through analyzing various authors, I have attempted to distill the information that is closest to my own beliefs and thoughts. While opinions among authors may differ, conclusions regarding anatomical, physiological, and technical characteristics and possibilities can be partly discerned and understood through personal experience. By examining the characteristics that frequently and consistently appear in inexperienced singers when improperly using passaggio, it is possible to determine mechanisms that can reconcile and bridge the differences between heavy and light vocal registration. I will begin by explaining the terms voice registers and passaggio, as well as their development throughout history, and then delve a bit more into the pedagogical procedures that are important for resolving issues related to them.