Jeremy Stoppelman, chief executive and co-founder of Yelp.com, defends his Web site as it deals with transparency issues. Some business owners and consumers are struggling to understand how user-generated sites, such as Yelp.com, operate. (Associated Press)

Jeremy Stoppelman, chief executive and co-founder of Yelp.com, defends his Web site as it deals with transparency issues. Some business owners and consumers are struggling to understand how user-generated sites, such as Yelp.com, operate. (Associated Press)