Go to the app store to install Product Reviews for Shopify
With the Product Reviews app, you can add a customer review feature to your products. This provides a way for your customers to engage with you, 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:
Google doesn't allow microdata information to be included in AdWords or Product Listing Ads. Your aggregate review scores will appear only in your organic search results. Ultimately, Google decides what data to display, which means your data might not show up all the time.