Google is the largest search engine of the web, and it has a variety of ways to enhance its search result experience.
One of which, is by using the 'scores' and/or the 'stars' review rich results. This little addition can be helpful, especially when users are searching for products or services, and comparing one to another.
And here, "To make them more helpful and meaningful, we are now introducing algorithmic updates to reviews in rich results. This also addresses some of the invalid or misleading implementations webmasters have flagged to us."
According to Google on its Webmaster blog post, webmasters can technically attach review markup to any schema type, for many types.
But since it may not add much value to users, Google is changing this, by "limiting the pool of schema types that can potentially trigger review rich results in search."
Specifically, according to Google, the search engine will only display reviews with the following types (and their respective subtypes):
And to make reviews more accurate, Google is not allowing self-serving reviews for local businesses and organizations.
"Reviews that can be perceived as 'self-serving' aren't in the best interest of users. We call reviews 'self-serving' when a review about entity A is placed on the website of entity A - either directly in their markup or via an embedded 3rd party widget," said Google.
"That’s why, with this change, we’re not going to display review rich results anymore for the schema types LocalBusiness and Organization (and their subtypes) in cases when the entity being reviewed controls the reviews themselves."
And also with this update, the name property is required.
What this means, webmasters should make sure that they specify the name of the item that's being reviewed.
"This update will help deliver a much more meaningful review experience for users, while requiring little to no changes on the part of most webmasters," closes Google.