As New is to be used only when the book is in the same immaculate condition in which it was published. There can be no defects, no missing pages, no library stamps, etc., and the dustjacket (if it was issued with one) must be perfect, without any tears (From the old AB Bookman's Describing Condition)

Not much needs to be added here. Purists note that even an Authorial signature or inscription disqualifies a book from being listed as "As New" since the book is no longer in the same condition as it was the day it rolled off the press.

Very Good can describe a used book that does show some small signs of wear - but no tears - on either binding or paper. Any defects must be noted. (From the old AB Bookman's Describing Condition)

A notch or two above the average used book you would find in your neighborhood used bookstore. If there are signs of reading, it was a careful reading. Any flaws of note will be called out.

Good describes the average used and worn book that has all pages or leaves present. Any defects must be noted. (From the old AB Bookman's Describing Condition)

An under-used grade. The most important thing for the neophyte book buyer to note is that a book graded "Good" really isn't that good. A "good" book is rarely anything but a place-keeper in a collector's library.

Fair is a worn book that has complete text pages (including those with maps or plates) but may lack endpapers, half-title, etc. (which must be noted). Binding, jacket (if any), etc. may also be worn. All defects must be noted. (From the old AB Bookman's Describing Condition)

This one should be self-explanatory.

Poor describes a book that is sufficiently worn that its only merit is as a Reading Copy because it does have the complete text, which must be legible. Any missing maps or plates should still be noted. This copy may be soiled, scuffed, stained or spotted and may have loose joints, hinges, pages, etc. (From the old AB Bookman's Describing Condition)

A poor book has no merits as a collectible but is viable for reading.

Ex-library copies must always be designated as such no matter what the condition of the book. (From the old AB Bookman's Describing Condition)

Book Club editions must always be noted as such no matter what the condition of the book.(From the old AB Bookman's Describing Condition)

Binding Copy describes a book in which the pages or leaves are perfect but the binding is very bad, loose, off, or nonexistent. (From the old AB Bookman's Describing Condition)