Google has released the fifth version of their Product Reviews Update on September 20th, a search engine algorithm update that is targeted at ranking product review-related content on the web that is most helpful and useful to searchers and users.
Google officially announced this on Twitter, as well as their Google updates pages here.
“A product reviews update aims to better reward high quality product reviews, content that provides insightful analysis and original research, and is written by experts or enthusiasts who know the topic well. Currently, this update only involves English searches globally.
A product reviews update works primarily to evaluate product review content on a page-level basis. However, for sites that have a substantial amount of product review content, any content within a site might be evaluated by the update. If you don’t have a lot of product reviews (a really substantial not-single-digit-percentage part of your entire site is made up of them), a site-wide evaluation is not likely to happen.
Structured data might help us better identify if something is a product review, but we don’t solely depend on it.”