SEO Rich Snippet Reviews Microdata for Product page
Schema.org reviews microdata and data-vocabulary.org Review-aggregate microdata for OpenCart product
The HTML5 microdata specification is a way to label content to describe a specific type of information—for example, reviews, person information, or events.
Each information type describes a specific type of item, such as a person, and event, or a review. For example, an event has the properties venue, starting time, name, and category.