All-Time Bestselling Books and Authors
Example Questions that can be answered by this FAQ:
One should bear in mind that this question is basically unanswerable. No one really knows which books have sold the most copies in history, because we simply don’t have records that cover all of history! As such, any answer that we find is essentially just a "best guess" that is based upon estimates made by historians and other experts.
With that in mind, here are links to help answer these questions.
Discovery's HowStuffWorks website has a page listing the 21 best-selling books of all time.
These websites provide popular weekly or periodic best-seller lists.
This Slate article from 1998, The Book Industry’s Best-Seller Lists - What are they, and why do they matter so much?, explains what a "best-seller" is and and how "best-seller" lists differ from one another.