What is a recommendation system, what applications do recommendation systems have to business? Briefly describe two approaches to building recommendation systems – compare the approaches. Offer a simple (worked) example of one of the approaches in action. What are some of the possible applications of recommendation systems to fields outside business? To what extent do recommendation systems similar to and support the implementation of personalisation? 300 words limit

A recommendation system is a subclass of information filtering system that seeks to predict the "rating" or "preference" a user would give to an item. They are primarily used in commercial applications.

Recommendation systems have significant value to businesses as they help to personalize a customer's online experience, leading to higher customer satisfaction and retention. They are used in a variety of areas, with commonly recognized ones being movie recommendations, music preferences, and shopping suggestions.

Two main approaches to building recommendation systems are collaborative filtering and content-based filtering. Collaborative filtering collects large amounts of information on users’ behaviors, activities or preferences and predicts what users will like based on their similarity to other users. A key advantage of the collaborative filtering approach is that it does not rely on machine analyzable content and therefore it is capable of accurately recommending complex items such as movies without requiring an "understanding" of the item itself.

Content-based filtering, on the other hand, uses a series of discrete characteristics of an item in order to recommend additional items with similar properties. Content-based filtering methods are based on a description of the item and a profile of the user's preferences.

For example, a content-based recommendation system for a movie streaming service could recommend movies based on a user's past viewing history. If a user frequently watches action movies, the system would recommend other action movies for them to watch.

Outside of business, recommendation systems can be applied in various fields like education (recommendation for courses, books), healthcare (recommendation for doctors, treatments), and more.

Recommendation systems are a key component of personalization strategies. They allow businesses to provide their customers with highly relevant content, products, and services on an individual level. The more a company can personalize the user experience, the more likely they are to retain their customers and increase their overall customer lifetime value.