Recommender systems are AI-based algorithms that use different information to recommend products to customers. We can say that recommender systems are a subtype of machine learning because the algorithms “learn from their past,” i.e., use past data to predict the future.
Today, we’re exposed to vast amounts of information. The internet is overflowing with data on virtually any topic. Recommender systems are like filters that analyze the data and offer the users (you) only relevant information. Since what’s relevant to you may not interest someone else, these systems use unique criteria to provide the best results to everyone.
In this article, we’ll dig deep into recommender systems and discuss their types, applications, and challenges.
Types of Recommender Systems
Learning more about the types of recommender systems will help you understand their purpose.
Content-Based Filtering
With content-based filtering, it’s all about the features of a particular item. Algorithms pick up on specific characteristics to recommend a similar item to the user (you). Of course, the starting point is your previous actions and/or feedback.
Sounds too abstract, doesn’t it? Let’s explain it through a real-life example: movies. Suppose you’ve subscribed to a streaming platform and watched The Notebook (a romance/drama starring Ryan Gosling and Rachel McAdams). Algorithms will sniff around to investigate this movie’s properties:
- Genre
- Actors
- Reviews
- Title
Then, algorithms will suggest what to watch next and display movies with similar features. For example, you may find A Walk to Remember on your list (because it belongs to the same genre and is based on a book by the same author). But you may also see La La Land on the list (although it’s not the same genre and isn’t based on a book, it stars Ryan Gosling).
Some of the advantages of this type are:
- It only needs data from a specific user, not a whole group.
- It’s ideal for those who have interests that don’t fall into the mainstream category.
A potential drawback is:
- It recommends only similar items, so users can’t really expand their interests.
Collaborative Filtering
In this case, users’ preferences and past behaviors “collaborate” with one another, and algorithms use these similarities to recommend items. We have two types of collaborative filtering: user-user and item-item.
User-User Collaborative Filtering
The main idea behind this type of recommender system is that people with similar interests and past purchases are likely to make similar selections in the future. Unlike the previous type, the focus here isn’t just on only one user but a whole group.
Collaborative filtering is popular in e-commerce, with a famous example being Amazon. It analyzes the customers’ profiles and reviews and offers recommended products using that data.
The main advantages of user-user collaborative filtering are:
- It allows users to explore new interests and stay in the loop with trends.
- It doesn’t need information about the specific characteristics of an item.
The biggest disadvantage is:
- It can be overwhelmed by data volume and offer poor results.
Item-Item Collaborative Filtering
If you were ever wondering how Amazon knows you want a mint green protective case for the phone you just ordered, the answer is item-item collaborative filtering. Amazon invented this type of filtering back in 1998. With it, the e-commerce platform can make quick product suggestions and let users purchase them with ease. Here, the focus isn’t on similarities between users but between products.
Some of the advantages of item-item collaborative filtering are:
- It doesn’t require information about the user.
- It encourages users to purchase more products.
The main drawback is:
- It can suffer from a decrease in performance when there’s a vast amount of data.
Hybrid Recommender Systems
As we’ve seen, both collaborative and content-based filtering have their advantages and drawbacks. Experts designed hybrid recommender systems that grab the best of both worlds. They overcome the problems behind collaborative and content-based filtering and offer better performance.
With hybrid recommender systems, algorithms take into account different factors:
- Users’ preferences
- Users’ past purchases
- Users’ product ratings
- Similarities between items
- Current trends
A classic example of a hybrid recommender system is Netflix. Here, you’ll see the recommended content based on the TV shows and movies you’ve already watched. You can also discover content that users with similar interests enjoy and can see what’s trending at the moment.
The biggest strong points of this system are:
- It offers precise and personalized recommendations.
- It doesn’t have cold-start problems (poor performance due to lack of information).
The main drawback is:
- It’s highly complex.
Machine Learning Techniques in Recommender Systems
It’s fair to say that machine learning is like the foundation stone of recommender systems. This sub-type of artificial intelligence (AI) represents the process of computers generating knowledge from data. We understand the “machine” part, but what does “learning” implicate? “Learning” means that machines improve their performance and enhance capabilities as they learn more information and become more “experienced.”
The four machine learning techniques recommender systems love are:
- Supervised learning
- Unsupervised learning
- Reinforcement learning
- Deep learning
Supervised Learning
In this case, algorithms feed off past data to predict the future. To do that, algorithms need to know what they’re looking for in the data and what the target is. The data in which we know the target label are named labeled datasets, and they teach algorithms how to classify data or make predictions.
Supervised learning has found its place in recommender systems because it helps understand patterns and offers valuable recommendations to users. It analyzes the users’ past behavior to predict their future. Plus, supervised learning can handle large amounts of data.
The most obvious drawback of supervised learning is that it requires human involvement, and training machines to make predictions is no walk in the park. There’s also the issue of result accuracy. Whether or not the results will be accurate largely depends on the input and target values.
Unsupervised Learning
With unsupervised learning, there’s no need to “train” machines on what to look for in datasets. Instead, the machines analyze the information to discover hidden patterns or similar features. In other words, you can sit back and relax while the algorithms do their magic. There’s no need to worry about inputs and target values, and that is one of the best things about unsupervised learning.
How does this machine learning technique fit into recommender systems? The main application is exploration. With unsupervised learning, you can discover trends and patterns you didn’t even know existed. It can discover surprising similarities and differences between users and their online behavior. Simply put, unsupervised learning can perfect your recommendation strategies and make them more precise and personal.
Reinforcement Learning
Reinforcement learning is another technique used in recommender systems. It functions like a reward-punishment system, where the machine has a goal that it needs to achieve through a series of steps. The machine will try a strategy, receive back, change the strategy as necessary, and try again until it reaches the goal and gets a reward.
The most basic example of reinforcement learning in recommender systems is movie recommendations. In this case, the “reward” would be the user giving a five-star rating to the recommended movie.
Deep Learning
Deep learning is one of the most advanced (and most fascinating) subcategories of AI. The main idea behind deep learning is building neural networks that mimic and function similarly to human brains. Machines that feature this technology can learn new information and draw their own conclusions without any human assistance.
Thanks to this, deep learning offers fine-tuned suggestions to users, enhances their satisfaction, and ultimately leads to higher profits for companies that use it.
Challenges and Future Trends in Recommender Systems
Although we may not realize it, recommender systems are the driving force of online purchases and content streaming. Without them, we wouldn’t be able to discover amazing TV shows, movies, songs, and products that make our lives better, simpler, and more enjoyable.
Without a doubt, the internet would look very different if it wasn’t for recommender systems. But as you may have noticed, what you see as recommended isn’t always what you want, need, or like. In fact, the recommendations can be so wrong that you may be shocked how the internet could misinterpret you like that. Recommender systems aren’t perfect (at least not yet), and they face different challenges that affect their performance:
- Data sparsity and scalability – If users don’t leave a trace online (don’t review items), the machines don’t have enough data to analyze and make recommendations. Likewise, the datasets change and grow constantly, which can also represent an issue.
- Cold start problem – When new users become a part of a system, they may not receive relevant recommendations because algorithms don’t “know” their preferences, past purchases, or ratings. The same goes for new items introduced to a system.
- Privacy and security concerns – Privacy and security are always at the spotlight of recommender systems. The situation is a paradox. The more a system knows about you, the better recommendations you’ll get. At the same time, you may not be willing to let a system learn your personal information if you want to maintain your privacy. But then, you won’t enjoy great recommendations.
- Incorporating contextual information – Besides “typical” information, other data can help make more precise and relevant recommendations. The problem is how to incorporate them.
- Explainability and trust – Can a recommender system explain why it made a certain recommendation, and can you trust it?
Discover New Worlds with Recommender Systems
Recommender systems are growing smarter by the day, thanks to machine learning and technological advancements. The recommendations were introduced to allow us to save time and find exactly what we’re looking for in a jiff. At the same time, they let us experiment and try something different.
While recommender systems have come a long way, there’s still more than enough room for further development.
Related posts
2025 has come to a close, with 2026 already underway. There are many exciting events ahead and future milestones to aim for and look forward to. But it’s also the ideal time to look back over the last 12 months, exploring the most notable achievements we’ve made, lessons we’ve learned, and important moments to reflect on as the new year continues for OPIT’s staff, students, and broader community.
1. Student Commitment
Studying isn’t always easy. It involves long days, and even long evenings sometimes, with a seemingly never-ending series of tasks to accomplish and goals to aim for. It can take a lot out of even the most hard-working and dedicated individuals.
Yet, despite the hardships and challenges, OPIT students demonstrated remarkable resilience, continuous curiosity, and indefatigable determination throughout 2025. Looking back on the year, students at all levels of the OPIT community should feel proud and celebrate their accomplishments.
2. Podcast Launch
2025 saw a lot of new arrivals at OPIT, with fresh projects and innovations arriving on the scene. Chief among them was the OPIT EDGE Podcast, an exciting addition to the institute’s ever-expanding multimedia offerings.
There have already been several episodes of the podcast for students and technology enthusiasts in general to enjoy, with the first episode of this student-driven project involving an in-depth discussion with industry expert Matteo Zangani on the potential of quantum AI technology.
3. Success Stories
While many new students have joined the OPIT ranks in 2025 and will also do so in 2026, others have now achieved their educational objectives and are already moving on to the next exciting steps and chapters in their personal and professional lives.
There are so many inspiring success stories from the last 12 months, it’s impossible to list them all. But just one notable example has to be Maria Brilaki, who recently concluded her Master’s in Responsible AI, defending a powerful thesis related to non-invasive glucose monitoring through near-infrared spectroscopy and machine learning.
4. Graduation in Malta
2025 was a big year of firsts for OPIT, including the institute’s first official graduation ceremony, which took place on March 8 at a grand ceremony in Malta, honoring the achievements of dozens of applied data science and AI graduates.
The hybrid event was open to both in-person and virtual attendees, bringing together members of the OPIT community from across the world. It was a huge moment for the graduates themselves and a thrilling milestone for OPI – a testament to all the hard work that has gone into building this institute.
5. OPIT AI Copilot
Artificial intelligence is the technology of the moment, and OPIT isn’t just dedicated to teaching the next-generation of technology leaders how to work with AI responsibly and efficiently; it’s also interested in harnessing the powers and potential of AI to improve its educational offerings, too.
This culminated in the development and release of OPIT AI Copilot in 2025. This groundbreaking AI tool now provides real-time, personalized learning support, along with contextual assistance, and is available on a round-the-clock basis for students to turn to, as and when they feel the need.
6. Hackathons
2025 also saw OPIT students and faculty take more active roles in various events, including hackathons. In November, for example, OPIT got involved with the 6th edition of the ESCP Hackathon, with several students entering as developers.
This was an exciting and unique opportunity for those students to meet up in person, put the skills they’ve honed during their time at OPIT to the test in a challenging environment, and learn from one another. OPIT will surely participate in more hackathons in the years to come, so stay tuned for more details on upcoming events and how you can play your part.
7. Strengthening Collaboration
From day one, OPIT has focused on building a strong network of established technology and business partners, opening doors and providing opportunities for both education and employment for its students.
This continued throughout 2025, with OPIT strengthening its connections with a number of world-leading organizations, including Accenture, AWS, Hype, Buffetti, and more. Through events like hackathons, career fairs, and more, OPIT makes the most of its ever-expanding and increasingly impressive professional network.
8. Online Career Fair
Another big first for 2025 was the inaugural OPIT Online Career Fair, an event that was held on November 19 and 20, with more than a dozen established and emerging companies from around the world in attendance, including the likes of Deloitte, Tinexta Cyber, Datapizza, RWS Group, Planet Farms, and Nesperia Group.
The only nature of this event ensured that students all enjoyed equal access, no matter where they were based, and everyone was able to hear from industry experts and enjoy the unique array of opportunities on offer, forging their own connections and learning more about brands they might like to work with or for in the future.
9. Education Innovation
OPIT has always been about innovating, delivering newer and smarter ways to learn for students across the globe, no matter their background, budget, or social class. And the institute has continually innovated over the course of 2025, helping students learn skills and broaden their knowledge efficiently and intuitively.
As we enter 2026, OPIT’s innovation is set to be on full display once more, with no less than two new courses for new applicants to choose from: AI-Driven Software Development (Elective) and Business Intelligence and Decision Making (Elective).
10. The Power of the OPIT Community
Perhaps the crowning achievement for OPIT in 2025 was the demonstrable success of not just individual students or faculty members, but the entire OPIT community, as a whole. Everyone, from alumni to new students and seasoned staff members, played their part in the institute’s success, paving the way for more great things and major milestones in 2026 and beyond.
As OPIT Rector and former Italian Minister of Education, Francesco Profumo, puts it:
“What inspires me most is the mindset of our students: forward-looking, responsible, and driven by a desire not just to succeed, but to contribute. Their dedication reminds us why education remains one of the most powerful forces for shaping the future.”
Bring talented tech experts together, set them a challenge, and give them a deadline. Then, let them loose and watch the magic happen. That, in a nutshell, is what hackathons are all about. They’re proven to be among the most productive tech events when it comes to solving problems and accelerating innovation.
What Is a Hackathon?
Put simply, a hackathon is a short-term event – often lasting just a couple of days, or sometimes even only a matter of hours – where tech experts come together to solve a specific problem or come up with ideas based on a central theme or topic. As an example, teams might be tasked with discovering a new way to use AI in marketing or to create an app aimed at improving student life.
The term combines the words “hack” and “marathon,” due to how participants (hackers or programmers) are encouraged to work around-the-clock to create a prototype, proof-of-concept, or new solution. It’s similar to how marathon runners are encouraged to keep running, putting their skills and endurance to the test in a race to the finish line.
The Benefits of Hackathons
Hackathons provide value both for the companies that organize them and the people who take part. Companies can use them to quickly discover new ideas or overcome challenges, for example, while participants can enjoy testing their skills, innovating, networking, and working either alone or as part of a larger team.
Benefits for Companies and Sponsors
Many of the world’s biggest brands have come to rely on hackathons as ways to drive innovation and uncover new products, services, and opportunities. Meta, for example, the brand behind Facebook, has organized dozens of hackathons, some of which have led to the development of well-known Facebook features, like the “Like” button. Here’s how hackathons help companies:
- Accelerate Innovation: In fast-moving fields like technology, companies can’t always afford to spend months or years working on new products or features. They need to be able to solve problems quickly, and hackathons create the necessary conditions to deliver rapid success.
- Employee Development: Leading companies like Meta have started to use annual hackathons as a way to not only test their workforce’s skills but to give employees opportunities to push themselves and broaden their skill sets.
- Internal Networking: Hackathons also double up as networking events. They give employees from different teams, departments, or branches the chance to work with and learn from one another. This, in turn, can promote or reinforce team-oriented work cultures.
- Talent Spotting: Talents sometimes go unnoticed, but hackathons give your workforce’s hidden gems a chance to shine. They’re terrific opportunities to see who your best problem solvers and most creative thinkers at.
- Improving Reputation: Organizing regular hackathons helps set companies apart from their competitors, demonstrating their commitment to innovation and their willingness to embrace new ideas. If you want your brand to seem more forward-thinking and innovative, embracing hackathons is a great way to go about it.
Benefits for Participants
The hackers, developers, students, engineers, and other people who take part in hackathons arguably enjoy even bigger and better benefits than the businesses behind them. These events are often invaluable when it comes to upskilling, networking, and growing, both personally and professionally. Here are some of the main benefits for participants, explained:
- Learning and Improvement: Hackathons are golden opportunities for participants to gain knowledge and skills. They essentially force people to work together, sharing ideas, contributing to the collective, and pushing their own boundaries in pursuit of a common goal.
- Networking: While some hackathons are purely internal, others bring together different teams or groups of people from different schools, businesses, and places around the world. This can be wonderful for forming connections with like-minded individuals.
- Sense of Pride: Everyone feels a sense of pride after accomplishing a project or achieving a goal, but this often comes at the end of weeks or months of effort. With hackathons, participants can enjoy that same satisfying feeling after just a few hours or a couple of days of hard work.
- Testing Oneself: A hackathon is an amazing chance to put one’s skills to the test and see what one is truly capable of when given a set goal to aim for and a deadline to meet. Many participants are surprised to see how well they respond to these conditions.
- Boosting Skills: Hackathons provide the necessary conditions to hone and improve a range of core soft skills, such as teamwork, communication, problem-solving, organization, and punctuality. By the end, participants often emerge with more confidence in their abilities.
Hackathons at OPIT
The Open Institute of Technology (OPIT) understands the unique value of hackathons and has played its part in sponsoring these kinds of events in the past. OPIT was one of the sponsors behind ESCPHackathon 6, for example, which involved 120 students given AI-related tasks, with mentorship and guidance from senior professionals and developers from established brands along the way.
Marco Fediuc, one of the participants, summed up the mood in his comments:
“The hackathon was a truly rewarding experience. I had the pleasure of meeting OPIT classmates and staff and getting to know them better, the chance to collaborate with brilliant minds, and the opportunity to take part in an exciting and fun event.
“Participating turned out to be very useful because I had the chance to work in a fast-paced, competitive environment, and it taught me what it means to stay calm and perform under pressure… To prospective Computer Science students, should a similar opportunity arise, I can clearly say: Don’t underestimate yourselves!”
The new year will also see the arrival of OPIT Hackathon 2026, giving more students the chance to test their skills, broaden their networks, and enjoy the one-of-a-kind experiences that these events never fail to deliver. This event is scheduled to be held February 13-15, 2026, and is open to all OPIT Bachelor’s and Master’s students, along with recent graduates. Interested parties have until February 1 to register.
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