Updated: Aug 9, 2019
Look, I'm an avid reader and buyer of books, just like you. I've probably purchased upwards of 100 books on Amazon alone - and that's most certainly LESS than many other fans of literature. I've done it too... we've all done it.
We purchased a book. We read it. We loved it.
And then we move on with our lives.
To a writer, this is akin to one of those bosses in the office who just NEVER gives you a "good job" or a pat on the back, even when you excelled at doing something. To a writer, a review is SO critical. For MANY reasons - hopefully I'll be able to outline them here for you. I'll start with the mental reasons, or the "non-marketing" reasons, that a review is so imperative.
Writing is a tough job. It's a tough hobby, it's a tough career, and it's a tough industry to be in. It can also be expensive. No matter what genre or niche a writer has carved out for themselves, the literary industry is SATURATED with authors, self-published or backed by giant publishing houses, who all want their books to be read. A lot of times a writer has to fight the inner struggles and familiar feelings of failure and anti-climactic book launches and releases. They slave, for months or sometimes years, behind their computer screens, oozing their very lives into their stories, putting countless hours of research and mind-numbing episodes of imaginative mania into a finished product that you as the reader can enjoy. Don't get me wrong - every author loves doing this. It's why they write to begin with, among, most likely, a multitude of other reasons. But still, the fact remains that writing a good book or story is A LOT of work. A LOT. It is very taxing, very rewarding, and a very slow process. This is followed by, many times and for many authors, an invisible launch with little to no book sales, unless they're a well-known name backed by the powers of established publishers... and even THEN a successful book is not guaranteed. A quick search on Google will tell you that most authors don't even make $10,000 a year, and this seems pretty accurate. All of this has helped deliver the popular phrase "starving author."
A review, and especially a GROUP of reviews, that critique the book (whether positive or not) means the WORLD for ANY author, indie and self-published or mainstream and sponsored alike. It shows us that people have DISCOVERED our projects. And if they enjoyed it, it shows us that we did SOMETHING to contribute to the quality of life of that reader, no matter how small. And if it's a negative review, it shows us that readers have INVESTED themselves in our stories, have critiqued it in a way that shows support through the criticism. Negative feedback is still feedback. Reviews keep authors going.
Now for the marketing reasons; they're pretty self-explanatory. On e-commerce websites such as Amazon, reviews give authors and their books visibility. I forget what the numbers are to tell you the truth, but they're something like after 25 reviews you get featured on Amazon Newsletters, 50 reviews you get added to the Sponsored Products reel, and 75 reviews you get Featured Spotlights. Something along those lines, but don't quote me on that. The fact is that the more reviews a book has, the more sales it generates; how many times have you skipped out on an Amazon product you were looking at purchasing because it had no reviews? Or bad reviews? Reviews = sales. Sales = additional marketing. Amazon is trying, tirelessly, to always direct traffic to their site and to create sales. There comes a point when an Amazon product has generated enough buzz that the e-commerce giant begins to market it FOR YOU, as they're smart enough, with enough technical algorithms behind their site, to know that this product = traffic, sales, clicks, etc.
And let's face it. No-one markets a book, or anything for that matter, like Amazon does.
Other e-commerce sites for books, such as Barnes and Noble and Kobo, work with similar algorithms and marketing strategies.
Reviews cost us, as readers, nothing. It's just like tipping your waiter at Applebee's when he does a good job, or tipping your bartender at the Ale House when they hook you up with a magnificent cocktail. Heck, those actually cost you extra money - reviews don't!
Next time you love a book, or even dislike it, consider leaving a review. Consider finding the five minutes in your day to let that author know how they impacted you with their story. Consider giving that author reason to keep going. Consider contributing to that author's success and livelihood so that they can continue to write stories for the masses, continue to CREATE in a world that CONSUMES. It truly is the cheapest impact you can make. :-)