A "first edition book" refers to the very first printing of a book, which is often considered the most valuable version. This edition is significant because it represents the author's original work before any changes or corrections were made in subsequent printings. Collectors and bibliophiles often seek first editions for their rarity and historical importance. First editions can vary in value based on factors such as the book's popularity, the author's reputation, and the condition of the book. Notable first editions include classics like Moby Dick by Herman Melville and The Great Gatsby by F. Scott Fitzgerald, which are highly sought after by collectors.