In a collaborative filtering-based recommendation system, there are dimensions of entities: users and items (items refers to products, such as movies, games, and songs). As a user, you might have preferences for certain items. Therefore, these preferences must be motivated out of the data about items, users, or ratings. This data is often represented as a utility matrix, such as a user-item pair. This type of value can represent what is known about the degree of preference that the user has for a particular item.
The following table shows an example utility matrix that represents the rating users have given to movies on a 1-5 scale, with 5 being the highest rating. HP1, HP2, and HP3 are acronyms for Harry Potter I, II