Collaborative filtering is a technique used by recommender systems. Collaborative filtering has two senses, a narrow one and a more general one.

What is meant by collaborative filtering?

In the newer, narrower sense, collaborative filtering is a method of making automatic predictions (filtering) about the interests of a user by collecting preferences or taste information from many users (collaborating).

What is collaborative filtering and its types?

There are two classes of Collaborative Filtering:

User-based, which measures the similarity between target users and other users. Item-based, which measures the similarity between the items that target users rate or interact with and other items.