Some people who read but don’t write, won’t understand how imperative book reviews are to a books success. There is more to a review than just saying whether it’s good or not. Although, that is its primary purpose. Often reviews are used to bring a book to its ideal reader and much more.
A books exposure is often tied to its numerical value. Amazon being the leading distributor of books has a scale of stars ranging from one to five. The higher the star value, the higher it makes it on the website, giving it more visibility. Also, if a book has a higher rating, it sometimes makes special lists based on genre or what’s trending. I’ve heard that the magic number for Amazon is fifty from multiple authors.
During my twenties I wrote book reviews for my local papers. A compilation of some can be found here on this site, but also new ones. In most of those cases, the books had already been popular for years, so they didn’t need exposure. When reviewing a new book or one written by someone I know, I often leave a review on Amazon. There are other popular sites that use this review system like Goodreads too. I hope you keep this in mind as you go through your reading journey.