As a reader I scroll through reviews to give me insight on the book and if it's something I will like. Even though I read reviews, I never left one for a book. I know I'm horrible for doing that, but now whenever I read a book I make sure to leave a review afterwards. I'm even going back and writing reviews for some of the old books I've read.
Most readers don't think reviews are important and are a waste of time, but reviews are helpful to authors and other readers. You may think your review isn't going to matter, especially if a book already has dozens of them. Each review is just as valuable as the next one, you may not know it but your review will help a reader decide whether to buy the book or not.
Authors will tell you book promotion is tough, with millions of books out there it's hard for an author to get noticed. They rely on various forms of promotion to help them, but reviews are the most crucial. In order to get reviews authors will contact blogs, host giveaways, and most of the time reduce the price to free. All they ask in return is for readers to leave a review, but most of the time nobody writes one.
I want all readers to take a second and picture themselves in the author's shoes. How would you feel spending months writing a book and promoting your heart out, yet you don't have anything to show for it, not even a review.
So the next time you read a book, take a few minutes to write a review. You'll be helping someone out.