Book collectors new and old should always be aware of the terms of the trade, especially when trying to understand exactly what you may be buying based solely on a catalog description, on paper or online. For many years now, a wonderful book called ABC For Book Collectors has been in print, written by John Carter originally and revised by Nicholas Barker. Serious and humorous at the same time, with every part of the book and book trade informatively described, the contents of this book are very useful to the Tolkien collector.
Just recently, ILAB (the International League of Antiquarian Booksellers) was given permission by Oak Knoll Press and the British Library to put the entire book online for free as a PDF document, for non-commercial use only. Having a copy that can be digitally searched is indispensable, whether or not you own a hard-copy. Head over there now to download it before it's gone, and support Oak Knoll and ILAB with your thanks for this wonderful gift. Happy collecting!