system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are so many books "bestsellers?"

Almost every book cover I've seen (even brand new books a week after release!) are labeled as "bestseller." From my understanding of English, BEST means #1, which only one book can take. So why are there hundreds, and maybe thousands of bestsellers?
gpt
It doesn't have to be #1 to be a bestseller. Every week, the New York Times publishes their lists of bestselling books. They are divided by category and format (fiction, non-fiction, e-book, print, hardcover & paperback). If a book was listed as the #10 best-selling book for young adults by NYT last week, the book could legitimately be called a bestseller.

And that's just the New York Times list. Other publications have lists as well, and they often feature different books. Amazon's lists get updated every hour. If you have a book that shows up on their top 100 list for an hour, you are an Amazon Bestselling Author.