hReview is a microformat for publishing reviews of books, music, films, restaurants, businesses, holidays, etc.Microformats: Empowering Your Markup for Web 2.0 (2007) by John Allsopp p. 200 using (X)HTML on web pages, using HTML classes and rel attributes.
On the 12th of May 2009, Google announced that they would be parsing the hReview, hCard and hProduct microformats, and using them to populate search result pages.
References
External links hReview at the Microformats Wiki