Collaborative filtering is the process of filtering for information or patterns using techniques including collaboration among multiple agents, viewpoints, data sources, and so on. Collaborative filtering methods have been applied to many different kinds of data, including sensing and monitoring data, such as mineral exploration, environmental sensing over large areas or multiple sensors; financial data, such as financial service institutions that integrate many financial sources; or in electronic commerce and web applications where the focus is on user data and so on.

The basic principle behind the collaborative filtering approach is that it tries to find people who are similar to each other by looking at their tastes. Let's say if a person primarily likes action movies, then it will try to find a person who has seen similar kinds of movies and it will try to recommend the one that hasn't been seen by the first person, but...