This book is an excellent guide to collecting Pokemon cards. I don't play the game myself, but I have collected my fair share of cards throughout my Pokemon loving youth. This guide explains to the non-player all the important markings on a card and what they mean. I now know the difference between rare, and secret rare, and how to get a baseline estimate if I wanted to ever sell my meager collection. This edition is up to date on the Sun and Moon line, and goes as far back as to the first generation cards I used to get at Zellers as a kid. The only thing missing that I would be interested in is the values assigned to the pins and figures that also ship with some card sets, as I have amassed a collection of pins as well.
This guide is worth the read if you too have a secret Pokemon collection that you want to be more informed about, or you plan on diving into starting a collection.