An advance reading copy, often shortened to ARC, is a prepublication copy sent to reviewers, booksellers and the trade before a book goes on sale. Modern ARCs are usually paperbacks with printed covers, often with publication details, marketing plans or "Not for sale" on the cover.
How to spot it
Look for wording such as "Advance Reading Copy", "Uncorrected Proof" or "Not for Resale" on the cover or first page, a plain or simplified cover, a publication date and price on the back, and sometimes a letter from the editor. The text may differ from the published book, because changes were often made after the ARCs were printed.
What it does to value
For most books an ARC is a curiosity worth modest sums. For major authors and famous debuts, early copies can be valuable, because they precede the first edition and were printed in small numbers. ARCs that show textual differences from the published book, or that came from the author's own circle, interest collectors most. Many are marked not for sale, which is a matter for the publisher rather than a bar to collecting.
Our guide to proof copies and advance reading copies explains the difference between proofs and ARCs and what makes one collectable.