Google Search has shown reviews of places, movies, TV shows, and more for a while now. The reviews displayed in Search results were always limited to a few select websites, but no longer. Google will now aggregate reviews from up to three sites for any given place (and movies/TV shows/books/etc), as long as the sites implement Google's snippet markup and follow its guidelines. Reviews can either be from the site itself, or from user-created reviews submitted to the site (like Facebook).
In addition to normal reviews, qualifying publishers can also add their critic reviews to Search results. As seen in the right screenshot above, these are larger cards with an embedded summary. Critic reviews are supported for local businesses, movies, as well as books.
Adding support for this new functionality into review sites is not very difficult, so expect to see more review sites show up as time goes on.
- Google Webmaster Central Blog