# Trends, Problems And Solutions of Recommender System
## 3 Types of Recommender System
-Content Based
-Collaborative
-Hybrid (Content & Collaborative)
## Favourite Quote

*“Getting information off the internet is like taking a drink from a fire hydrant”.*
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## What excatly is "Recommender System" (AKA "Recommendation System")
A RS (Recommender System) provides a solution for this by allocating suggestions for the items to be of use to the user.
## Personalized & Non-personalized RS
Personalized RS will based on past activities of the individual. Non-personalized RS recommends products to customer based on what other customers have said about the products on average. The recommendations are not dependent on the customers, so each customer will gets the same recommendations.
## Categories of RS
1. Content-based Filtering Systems: Uses information of active users and data about the items.
2. Collaborative Filtering Systems: Uses information about a set of users and their relations with the item to provide recommendations to the active user.
3. Demographic Filtering Systems: Uses demographic information such as age, gender, education, etc. of people for identiifying types of user.
4. Hybrid recommender Systems: By putting trustworthiness as a forward feature, it uses combination of content-based and collaborative filtering.
## Challenges & solutions
-Cold-Start
-Privacy
-Scalability
-Sparsity
-Over-Specialization
-Freshness(Predeictability)

###### tags: `self-study`