This book is a collection of studies written from 1993 to 2017 by economists who worked or are still working at the National Bank of Romania. Specifically, the book contains nine such studies, of which eight make up the bulk of another book published in Romanian. I had the honour of being asked to write the forewords for both works. For this reason, the foreword to this book is vastly similar to the one worded for the book published in Romanian. The two forewords are different in that this one makes reference to the two papers that this book contains aside from the one in Romanian and, obviously, does not refer to the studies contained in the book published in Romanian but not included in this book, with three exceptions, about which I will warn the reader right before I refer to them. The reason why I will refer to those three studies, although they are not included in this book, is that they treat similar issues and are more recent. I will make the reader aware of the references to these three papers at the right moment.