You want to help your organic listings stand out in the search results – this is becoming increasingly important as more websites compete with you for visibility and clicks. Here’s how to add reviews to your site using schema structured data markup.
Google's thoughts on reviews are simple: don’t lie or mislead with your reviews. If you're a compensated reviewer, you need to say so. If you're writing a review for a product you use, say so. You'll get nailed falsifying reviews from third parties on your own site or on other sites, so don’t do it.