Yelp is a business directory service and crowd-sourced review forum, and a public company of the same name that is headquartered in San Francisco, California. The company develops, hosts and markets the Yelp.com website and the Yelp mobile app, which publish crowd-sourced reviews about businesses. It also operates an online reservation service called Yelp Reservations.
The company has been accused of using unfair practices to raise revenue from the businesses that are reviewed on its site – e.g., by presenting more negative review information for companies that do not purchase its advertising services or by prominently featuring advertisements of the competitors of such non-paying companies. The company has acknowledged these practices to some degree, while denying certain behavior. The company’s review system’s reliability has also been affected by the submission of fake reviews by external users, such as false positive reviews submitted by a company to promote its own business or false negative reviews submitted about competing businesses – a practice sometimes known as “astroturfing”, which the company has tried to combat in various ways.
Source – https://en.wikipedia.org/wiki/Yelp