The body of this review is essentially that reported in Giovannelli (2021b). There are additions that make the review up to date especially with the numerous references added.
This review article arises from what was presented by me as the introductory speech of the workshop "The Golden Age of Cataclysmic Variables and Related Objects - VI". Obviously for reasons of space and my limited knowledge this article will be subject to selective choices of the topics covered. However, it is my intention to provide the reader with a personal overview of the problems solved and to be solved in this fascinating field of the cataclysmic variables. Far be it
from me to claim to have treated the topic comprehensively.