Recommendation systems help people by recommending items which suit their preferences. In collaborative filtering approach, methods recommend items to the users from other users whose past activities are similar to the recommendee users.In this project a review of collaborative filtering (cf) area on recommendation systems are given. After the review three models named SVD, Biased SVD and NNMF that are categorized under dimensionality reduction topic of model-based collaborative filtering models are implemented along with a simple naive bayes probabilistic model.