# Recommender systems **URL:** \ **Category:** Unsupervised Learning, Recommenders, Reinforcement\ **Tags:** week-module-2\ **Created:** [September 9, 2022, 6:27pm UTC](https://community.deeplearning.ai/t/recommender-systems/201538 "2022-09-09T18:27:09Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Rabi3](https://avatars.discourse-cdn.com/v4/letter/r/3d9bf3/32.png) [@Rabi3](https://community.deeplearning.ai/u/Rabi3)\ **Post date:** [September 9, 2022, 6:27pm UTC](https://community.deeplearning.ai/t/recommender-systems/201538/1 "2022-09-09T18:27:09Z")
Why collaborative and content based filtering are considered unsupervised learining since we have output values (movies ratings) ---
**Author:** ![rmwkwok](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/rmwkwok/32/126977_2.png) [@rmwkwok](https://community.deeplearning.ai/u/rmwkwok)\ **Post date:** [September 9, 2022, 8:06pm UTC](https://community.deeplearning.ai/t/recommender-systems/201538/2 "2022-09-09T20:06:57Z")
Hello @Rabi3, welcome to our community! They are, as you said, supervised learning approaches. The first, second, and third week of this course are about unsupervised learning, recommenders, and reinforcement learning respectively. Cheers, Raymond ---
**Author:** ![Rabi3](https://avatars.discourse-cdn.com/v4/letter/r/3d9bf3/32.png) [@Rabi3](https://community.deeplearning.ai/u/Rabi3)\ **Post date:** [September 9, 2022, 9:03pm UTC](https://community.deeplearning.ai/t/recommender-systems/201538/3 "2022-09-09T21:03:48Z")
Oh, I thought all of them are unsupervised algorithms, Thank you for responding ---
**Author:** ![rmwkwok](https://sea1.discourse-cdn.com/dlai/user_avatar/community.deeplearning.ai/rmwkwok/32/126977_2.png) [@rmwkwok](https://community.deeplearning.ai/u/rmwkwok)\ **Post date:** [September 9, 2022, 9:05pm UTC](https://community.deeplearning.ai/t/recommender-systems/201538/4 "2022-09-09T21:05:27Z")
You are welcome @Rabi3! Raymond