Guitar Playing, Theory into Practice. Knowing what you’re playing is fun. Not knowing isn’t. Perhaps since the bebop era in jazz & certainly since the dawn of some of the great singer songwriters of the late 1960’s & 70’s & right up to the present day, musicians in popular styles of all instruments have been looking in much greater detail at how music is structured. This book is an attempt to write as concise a course as possible that musicians of any level can either read from cover to cover, or use as a reference when needed or desired.