• Category
  • >Machine Learning

What is Collaborative Filtering? Types, Working and Case Study

  • Soumyaa Rawat
  • Sep 18, 2021
What is Collaborative Filtering? Types, Working and Case Study title banner

What is Collaborative Filtering?  


Ever thought about how e-commerce sites recommend products to their customers while they are looking for something exactly like that? Ever wondered how Netflix recommends similar movies based on what we have recently watched or added to our watchlist? 


Artificial Intelligence technology has advanced to such an extent that the world can be perceived through the lens of this technology. 


With various techniques like deep learning, machine learning, and artificial neural networks, artificial intelligence tools and techniques have enabled the internet to become a black hole filled with information and entertainment. 


In this respect, it has also enabled the internet to recommend users or items to netizens active on the internet. 


(Must read - History of Artificial Intelligence )


A variety of machine learning applications and software use recommender systems that are empowered by machine learning techniques and tools for recommending their users’ similar items or products. 


Broadly, there are 2 types of recommendation techniques that are in use as of now. First, content-based filtering requires users to enter data that is then processed to produce desired outputs. 


For instance, a user logs in to his/her Netflix account and enters "Hollywood Romantic Movies'' in the search bar. The results obtained from this search are procured with the help of the content-based approach that works on the basis of content inputs. 


Second, the technique of collaborative filtering implies that computers produce outputs based on a user's past interaction on a platform. Herein, we shall understand this with an example. 


Let us suppose that an individual is inclined towards romanticism and likes to watch movies belonging to the romantic genre on his Netflix account. Perhaps whenever he logs in to his account, he will see a separate section that will only display recommended movies based on his past preferences and watch history. 


(Also read: Netflix case study)


Therefore, the technique of collaborative filtering filters information and infers from the past interaction of a user to recommend similar items or content material. In this blog, we shall learn about Collaborative Filtering at length. 


Recommendation systems, used on a variety of platforms like e-commerce sites, OTT platforms, and music streaming applications, employ the technology of Collaborative Filtering that further recommends items or users based on a user's historical browsing data. Be it Instagram that recommends people we may know or similar clothing items that resemble the items that we've just added to our carts, collaborative filtering is a leading technology in the contemporary scenario. 


The key to this technique is Collaborative Filtering that has only emerged in the 21st century as a powerful unsupervised machine learning algorithm.


How does it work?


As we have already learned, Collaborative Filtering is an important machine learning technique that helps a computer to filter information based on past interactions and data recorded on the user's end. 


Simply put, collaborative filtering algorithms produce similar results based on the user's historical data. For instance, it has been established that a user is interested in Pop songs. 


Perhaps the collaborative filtering algorithms in music streaming applications will record this interaction of the user and interpret that the user prefers Pop Genre over other genres. 


The recommendation system built-in with this technique will display other popular songs of the Pop Genre. This is how a collaborative filtering algorithm works. 


By recording past interactions of a user on a particular platform, the technique of collaborative filtering interprets and produces recommendation results with similar traits. 


"It's based on the idea that people who agreed in their evaluation of certain items are likely to agree again in the future." Collaborative Filtering in Recommender Systems 



Types of Collaborative Filtering 


Broadly, there are 2 types of Collaborative Filtering techniques that can be used by software and applications worldwide. They are as follows:-


  1. User-based Collaborative Filtering


As collaborative filtering procures its results from implicit data, it is able to retrieve information that users otherwise might not provide. The first class of collaborative filtering is the user-based approach. 


This approach narrows down users with the help of collaborative filtering that has similar behaviors, common contacts, and close demographics, and similar consumer behaviors. Social networking sites incorporate this approach to recommend users to other users based on their patterns of behavior. 


Moreover, this approach is also employed for targeted ads and suggested items based on other users who have similar choices and preferences. Among the various approaches of collaborative filtering, user-based collaborative filtering is the first approach that came into existence. 


A typical example of this approach is the 'suggested friends' category displayed in Facebook. This category recommends people that users might know based on their virtual contacts and similar preferences. 


(Suggested blog: AI algorithms/ models)



  1. Item-based Collaborative Filtering


A class of collaborative filtering techniques, item-based collaborative filtering refers to the recommendation of items or products using collaborative filtering.  


By measuring similarity among products and inferring respective ratings, items are recommended to users based on their historical data and interactive history.  


This class of collaborative filtering was invented and first used by Amazon in 1998. Even today, e-commerce sites like Amazon and Flipkart use item-based recommendation systems to recommend similar items or products to users by filtering them with the help of a user's past interactive data. 


With the statistical technique of Nearest Neighbour, the technique of Collaborative Filtering in this approach works effectively and presents users with legitimate recommendations that have only led to an increase in consumption. 



Case Studies of Collaborative Filtering 


In this segment, we will be looking at various real-world case studies that will help us to understand the role of collaborative filtering in a better manner. 




A social networking site that was launched in the year 2004, Facebook has pioneered the world of social networking that aims to connect people from one corner of the world to another. 


Currently led by Mark Zuckerberg, Facebook uses numerous techniques of AI that have advanced the social networking site. However, one of the most striking techniques used by this social media giant is Collaborative Filtering. 


Be it target marketing suggested friends, or discovering friends, collaborative filtering is a highly significant technique. 


"Facebook uses different recommender systems for different parts of the site. For example, the user timeline may use one algorithm, while the News section and Marketplace sections use other recommender systems to provide data it thinks is useful to the user. " Collaborative Filtering in Facebook 





An e-commerce website, Amazon is a retail platform that sells various commodities and acts as a middleman by connecting sellers and buys from worldwide. 


Launched in 1994, Amazon earlier traded in only books. By using a variety of the best machine learning tools for better performance and enhanced user interaction, Amazon also incorporates the collaborative filtering technique for its recommendation system


Since an e-commerce platform like Amazon has millions of users surfing through the platform, this technique is of great use to the company and its users. With a colossal technological interface, Amazon offers a user-based approach and an item-based approach for suggested products and similar items. 


All in all, the platform's item-based collaborative filtering has proved to be a useful system that has triggered the profit-making capacity of the business. 


What's more, this platform opts for item-based collaborative filtering more than a user-based approach in order to produce high-quality recommendations. At first, collaborative filtering had only one approach - a user-based approach. 


However, it was Amazon that developed an item-based approach that began to look at items rather than users. 





The third case study is based on one of the most renowned OTT platforms worldwide - Netflix. Known for its humongous entertainment collection and latest OTT content, Netflix was founded in 1997. 


With millions of users from around the world, the platform offers various recommendations to its users, thanks to a collaborative filtering movie recommendation system. 


"Recommendation algorithms are at the core of the Netflix product. They provide our members with personalized suggestions to reduce the amount of time and frustration to find something great to watch."

Collaborative Filtering Applications in Netflix  


In the most mundane schedule, a user could log in to his/her Netflix account and make the most out of the recommendations that are displayed at every step of the way. 


With so much to watch and learn from, platforms like Netflix have brought in the best of all worlds as they use recommender systems empowered by collaborative filtering approaches that narrow down our options, and work according to our preferences. 




To sum up, collaborative filtering is more than just a recommendation technique. It is about the way the internet understands us and offers us the best it can. To some, it might seem to be intrusive. 


However, it is utterly genius for a machine to learn our consumer patterns and recommend items based on who is using them and something that resembles our own choices. 


(Top reading: Content-based recommendation system in ML)


Technology has advanced to such an extent that today, machines are filling in the gaps for us. That said, the future of collaborative filtering and other such revolutionary techniques is brilliant on all fronts. 

Latest Comments

  • normangdrum789

    May 27, 2022

    In addition to writing high school essays and college assignments, many of the professional writers and editors who can handle. You will receive a top-quality custom essay, written by professional essay writer for every order you place with us. Our team of the best essay writers https://uk.bestessays.com/dissertation-writing.html has been where you are. They were once students like you and remember wishing for a helping hand with their custom essays, term papers, and other assignments that had to be submitted on or before deadlines. You can be sure that no deadline is impossible to meet.