User reviews have changed the way people shop. The internet is now a vast and highly competitive market place, where an increasing number of people purchase a variety of things. User reviews provide an insight into the product, its quality, and other parameters. Buyers often depend on user reviews to make the right decision.
User review sites are independent sites which provide us with reviews of various things. Some sites deal with reviews of niche items, while others may deal with a broad spectrum of commodities. For example, there may be a site that only focuses on user discussion about plastic injection moulding companies, while another review site may deal with supermarket reviews, deals and discussions related to groceries!
This is just an example to give you an idea as to how a review site may function and what types of products it may deal with. A review site is meant to contain objective and unbiased reviews; however, this can never be ascertained as nobody can be stopped from voicing their own opinion.
So for example, say, you are reading reviews of local restaurants. You cannot tell if a review has been written by the owner of the restaurant or a paying customer. However, the volume of reviews generally balances out the statistics.
Review sites usually generate support through advertising. That is, advertisers buy ad space on a review site. Price comparison sites also feature reviews, and generate hefty revenues from commissions by participating vendors.