What is it? What is the reason that allows us to train dogs to find whatever it is we seem to be seeking? Dogs are an amazing animal with a nose to prove it. There are also the advantages of being able to use this domesticated and loving animal to perform tasks for us just because they love the attention, food or the toy at the end of the task. There really is no greater joy than to watch your dog do what you have trained it to do and do it well. But how does this work? What is scent theory? Do we really know how and why our dogs do what they do? The word theory means an idea, an opinion in some cases. There is real science behind the structure and abilities of a dogs olfactory but a theory about what they do with that scent is just that, a theory. I have been a search and rescue K9 tracking and trailing handler for over 10 years and have been shown and made a believer out of a scent theory that works, and works well, not just on some dogs but all dogs I have worked with. In this book I will present what I was taught, what I have found to be realistic and workable and what can help you train your dog to become a master tracker, trailer, air scent, drug or cadaver dog. The information in this book is also derived from experiences of not only myself but many handlers I have worked with over the years, some in search and rescue and some from law enforcement.