What are the product recommendation algorithms of shopping websites?

This form can generally be divided into recommendation engine algorithms, mainly based on collaborative filtering, content-based recommendation and other algorithms. "What percentage of people who have bought this product have bought other products": collaborative filtering, project-based filtering, "people with similar interests have bought other products": collaborative filtering, user-based filtering, related product recommendation: content-based recommendation "Guess what you like" generally adopts mixed recommendation algorithm.