You can use the Product Reviews app to add a customer review feature to your products. This lets your customers engage with your business, as well as each other, to encourage sales.
The Product Reviews app supports Google microdata (sometimes referred to as "rich snippets" or "structured data"). The app automatically adds an aggregate review score that appears in your search results on Google, which helps to increase traffic from organic searches.
If you're using an Online Store 2.0 theme, then the Product Reviews app saves rating data in Product Rating and Product Rating Count standard metafields. This means that your rating data is stored as additional data with your product. Because this data is stored in standard metafields, it might be compatible with other apps. Other apps can also contribute to your product rating data by writing to these metafields.