A review aggregator is a system that collects reviews of products and services (such as films, books, video games, software, hardware and cars). This system stores the reviews and then uses them for purposes such as creating a website for users to view the reviews, selling information to third parties about consumer tendencies and creating databases for companies to know about their actual and potential customers. The system enables users to easily compare many different reviews of the same work. Many of these systems calculate an approximate average assessment, usually based on assigning a numeric value to each review according to the degree of positivity toward to the work.
Review aggregation sites can now have an economic impact on the creators of the items reviewed, especially in certain categories such as electronic games. Depending on aggregate scores achieved, company stock prices can rise or fall, as can royalty payment rates and employee bonuses.