This book has come about for a number of reasons. The primary one is that in many of my classes my delegates have expressed their pleasure at my ability to "demystify" what is seen by many as an almost impenetrable subject. I have been told that they like my real-life anecdotes and my ability to express the sometimes convoluted areas in a simple fashion has clarified the subject for them. The book is not intended to replace the five core publications but simply to try and explain the concepts raised in these core books in a form that is slightly more approachable than the reference books would initially suggest. The final word on any of these matters has to be in reading the source materials. These along with others are referenced at the back of the book.