This excerpt taken from the NFLX 10-K filed Mar 16, 2006.
The key to our merchandizing efforts is the personal recommendations generated by our recommendation service. All subscribers and site visitors are given many opportunities to rate titles and we have collected
approximately one billion ratings. The ratings from our recommendation service determine which available titles are displayed to a subscriber and in which order. In doing so, we help our subscribers quickly find titles they are more likely to enjoy. Ratings also determine which available titles are featured most prominently on our Web site to increase customer satisfaction and selection activity. Finally, data from our recommendation service is used to generate lists of similar titles. Subscribers often start from a familiar title and use our Recommendations link to find other titles they may enjoy. This has proven to be a powerful method for catalogue browsing and expanding library utilization.
We also provide our subscribers with detailed information about each title in our library which helps them select movies they will enjoy. This information may include: