Schema uses microdata, introduced with HTML5 – simple tags that describes website content in a way that makes it more easy for a search engine to break down and interpret. There are 2 areas of microdata to consider in Schema:
a) Itemscope & itemtype. Itemscope would involve tagging the salient points of the page for example, in a blog it could be the title, the author and any category labels from within the blog. Itemtype is basically categorisation – there is a category for reviews as part of the standard Schema hierarchy.
b) itemprop. This is where a website can really demonstrate value to the search engines. For a review site, t could be the brand, retailer, the number of reviews for the retailer/brand in question, associated ratings or review date.
If you are interested in implementing Schema.org, the first part in my view is a content assessment with a view to providing the ultimate Schema orientated result. This could mean aggregating review stats or adding in external/internal links to relevant information. Let Schema challenge you and your website to become more visible in search engine results pages.