* Netflix Prize, an open competition for the best collaborative filtering algorithm

Clay Shirky traces the origin of the term " social software " to Eric Drexler's 1987 discussion of " hypertext publishing systems " like the subsequent World Wide Web, and how systems of this kind could support software for public critical discussion, collaborative development, group commitment, and collaborative filtering of content based on voting and rating.

* GraphLab GraphLab collaborative filtering library, large scale parallel implementation of matrix decomposition methods ( in C ++) for multicore.

In general, collaborative filtering is the process of filtering for information or patterns using techniques involving collaboration among multiple agents, viewpoints, data sources, etc.

Applications of collaborative filtering typically involve very large data sets.

The remainder of this discussion focuses on collaborative filtering for user data, although some of the methods and approaches may apply to the other major applications as well.

In the newer, narrower sense, collaborative filtering is a method of making automatic predictions ( filtering ) about the interests of a user by collecting preferences or taste information from many users ( collaborating ).

The underlying assumption of the collaborative filtering approach is that if a person A has the same opinion as a person B on an issue, A is more likely to have B's opinion on a different issue x than to have the opinion on x of a person chosen randomly.

For example, a collaborative filtering recommendation system for television tastes could make predictions about which television show a user should like given a partial list of that user's tastes ( likes or dislikes ).

One of the techniques used for dealing with this problem is called collaborative filtering.

The motivation for collaborative filtering comes from the idea that people often get the best recommendation from someone with similar taste.

Typically, the workflow of a collaborative filtering system is:

A key problem of collaborative filtering is how to combine and weight the preferences of user neighbors.

This falls under the category of user-based collaborative filtering.

Alternatively, item-based collaborative filtering invented by Amazon. com ( users who bought x also bought y ), proceeds in an item-centric manner:

See, for example, the Slope One item-based collaborative filtering family.

Another form of collaborative filtering can be based on implicit observations of normal user behavior ( as opposed to the artificial behavior imposed by a rating task ).

Services like Reddit, YouTube, and Last. fm are typical example of collaborative filtering based media.

One scenario of collaborative filtering application is to recommend interesting or popular information as judged by the community.

Another aspect of collaborative filtering system can make more personalized recommendation by analyzing information from your past activity or the history of other users of similar taste.

As in the personalized recommendation scenario, new user or new item can always cause a problem, as there will be insufficient data for the collaborative filtering to work.

The COMPASS system allowed up to 6 users created point-to-point connections with one another ; the collaborative session only remained while at least one user stayed active, and would have to be recreated if all six logged out.

SourceForge Enterprise Edition is a collaborative revision control and software development management system.

Kuro5hin is powered by the Scoop collaborative system.

A primary emphasis of the district's Strategic Plan is a collaborative effort to design and build a Town Learning Community that will invigorate community support for the public education system.

At the Congress of Vienna, Castlereagh designed and proposed a form of collective and collaborative security for Europe, then called a Congress system.

GNU Savannah is a project of the Free Software Foundation initiated by Loïc Dachary, which serves as a collaborative software development management system for Free Software projects.

This system of classification was developed as a collaborative project by Robert B Fetter, PhD, of the Yale School of Management, and John D Thompson, MPH, of the Yale School of Public Health.

A collaborative system is designed to support multiple users modifying different sections of the plan at once ; for example, updating the areas they personally are responsible for such that those estimates get integrated into the overall plan.

In December 2004, Clarke began work on Dijjer, a distributed P2P web cache, and Indy, a collaborative music discovery system, both in conjunction with ChangeTv, a company founded by his long-time collaborator, Steven Starr, who later brought in Clarke and Oliver Luckett as co-founders.

* Electronic meeting system, a collaborative computer software

Basing its authority on the will of the people, and developing new systems to draw the highest and best wisdom of all humanity into the task of governing out world, the collaborative governing system would be capable of solving the problems which call into question the future of man, such as hunger, water, war, peace-keeping, pollution and energy.

: Examples of products created by means of commons-based peer production include Linux, a computer operating system ; Slashdot, a news and announcements website ; Kuro5hin, a discussion site for technology and culture ; Wikipedia, an online encyclopedia ; and Clickworkers, a collaborative scientific work.

The previous system set up internationally to address the needs of IDPs was referred to as the collaborative approach as the responsibility for protecting and assisting IDPs was shared among the UN agencies, i. e. UNHCR, Unicef, WFP, UNDP, Office of the High Commissioner for Human Rights, the inter-governmental organization IOM, the ICRC and International NGOs.

Liberty University estimates that the book storage and robotic retrieval system will occupy 7 % of the library, while 67 % will be reserved for collaborative meeting areas and student study spaces.

For a new item added, the collaborative filtering system would not be able to recommend it until it's rated by a substantial number of users.

As collaborative filtering methods recommend items based on users ’ past preferences, new users will need to rate sufficient number of items to enable the system to capture their preferences accurately and thus provides reliable recommendations.

Recommender systems or recommendation systems ( sometimes replacing " system " with a synonym such as platform or engine ) are a subclass of information filtering system that seek to predict the ' rating ' or ' preference ' that a user would give to an item ( such as music, books, or movies ) or social element ( e. g. people or groups ) they had not yet considered, using a model built from the characteristics of an item ( content-based approaches ) or the user's social environment ( collaborative filtering approaches ).

One of the most famous examples of Collaborative Filtering is item-to-item collaborative filtering ( people who buy x also buy y ), an algorithm popularized by Amazon. com's recommender system.

The Minnesota State Colleges and Universities system of distinct and collaborative institutions offers higher education that meets the personal and career goals of a wide range of individual learners, enhances the quality of life for all Minnesotans and sustains vibrant economies throughout the state.

It is expected that students will take advantage of the many collaborative academic efforts between the departments of the School and other colleges and universities, including those within the CUNY system.