This is so much more than a gig-bag version of theory; it is a more useful and complete product than I've seen for the curious guitarist than any other I've seen. It covers a wide range of topics in VERY accessible language, and provides enough depth to answer most questions that anyone from complete beginner up to an advanced musician might ask. MOST importantly it doesn't ever get bogged down in any overly-technical discussion like so many others. I knocked off a star only because it's good enough to be a full size book, but is only available in this format!!!