Rich Snippets in Google search results page available since May 12, 2009 give users convenient summary information about their search results at a glance from the structured data embedded in web pages.
Google then back in August 2015 started leveraging this technology in the critic reviews in the Knowledge Graph.
Now, with the last weeks launch of critic reviews for local businesses, Google has begun incorporating this semantic data into local business search results pages.
This Critic reviews feature is available across mobile, tablet, and desktop. It allow publishers to promote their content on local Knowledge Graph cards and expose their reviews to new audiences, whenever a local card is surfaced.
Critic reviews appear in Search results with a snippet from the critic, the critic's name and the publisher icon.
For now, Critics reviews feature is only available to english reviews for businesses in the US. But, very soon the support for many other languages and countries will get added.
To set up critic reviews for local entities, Publishers can select snippets of reviews from their sites and annotate them and the associated business with schema.org markup, explains Google.
For supported markup formats, Google understand a variety of formats, including the JSON-LD data format.
Google detailed the process that allow publishers to communicate to Google of their prefered "snippet, what URL is associated with the review and other metadata about the local business" that help Google ensure of showing the right review for the right entity.
Publishers interested can get started with critic reviews markup instructions here.