Neutral point of view (WP:NPOV) – All Wikipedia articles and other encyclopedic content must be written from a neutral point of view, representing significant views fairly, proportionately and without bias.
Verifiability (WP:V) – Material challenged or likely to be challenged, and all quotations, must be attributed to a reliable, published source. In Wikipedia, verifiability means that people reading and editing the encyclopedia can check that information comes from a reliable source.
No original research (WP:NOR) – Wikipedia does not publish original thought: all material in Wikipedia must be attributable to a reliable, published source. Articles may not contain any new analysis or synthesis of published material that serves to advance a position not clearly advanced by the sources.
These policies determine the type and quality of material that is acceptable in Wikipedia articles. Because they complement each other, they should not be interpreted in isolation from one another. The principles upon which these policy statements are based are not superseded by other policies or guidelines, or by editors' consensus. These three policy pages may be edited only to improve the application and explanation of the principles.
"No original research" (NOR) has its origins in the "neutral point of view" (NPOV) policy and the problem of dealing with undue weight and fringe theories. The core policy of Wikipedia, NPOV, is meant to provide a framework whereby editors with diverse, often conflicting, even opposing points of view can collaborate on the creation of an encyclopedia. It does so through the principle that while it is often hard for people to agree as to what is the truth, it is much easier for people to agree as to what they and others believe to be the truth. Therefore, Wikipedia does not use "truth" as a criterion for inclusion. Instead, it aims to account for different, notable views of the truth. First codified in February 2001, the objective of the NPOV policy is to produce an unbiased encyclopedia.
In the two years that followed, a good deal of conflict on article talk pages involved accusations that editors were violating NPOV, and it became clear that this policy, which provided a philosophical foundation for Wikipedia, needed to be supplemented. Wikipedians developed the concept of "verifiability" (V) as a way of ensuring the accuracy of articles by encouraging editors to cite sources; this concept was established as a policy in August 2003. Verifiability was also promoted as a way to ensure that notable views would be represented, under the assumption that the most notable views were easiest to document with sources. Notability is especially important because while NPOV encourages editors to add alternate and multiple points of view to an article, it does not claim that all views are equal. Although NPOV does not claim that some views are more truthful than others, it does acknowledge that some views are held by more people than others. Accurately representing a view therefore also means explaining who holds the view and whether it is a majority or minority view.
Soon it became evident that editors who rejected a majority view would often marshal sources to argue that a minority view was superior to a majority view—or would even add sources in order to promote the editor's own view. Therefore, the NOR policy was established in 2003 to address problematic uses of sources. The original motivation for NOR was to prevent editors from introducing fringe views in science, especially physics—or from excluding verifiable views that, in the judgement of editors, were incorrect. It soon became clear that the policy should apply to any editor trying to introduce their own views into an article. This also led to the refinement and creation of sub sections dealing with the balance of coverage.
In its earliest form, the policy singled out edits for exclusion that:
Introduce a theory or method of solution;
Introduce original ideas;
Define existing terms in different ways; or introduce neologisms;
and established as criteria for inclusion edits that present:
Ideas that have been accepted for publication in a peer-reviewed journal; or
Ideas that have become newsworthy: they have been repeatedly and independently reported in newspapers or news stories (such as the cold fusion story).
As a more diverse community of editors were drawn to Wikipedia, it became clear that other topics besides physics, such as politics, religion, and history, were attracting original research. The need arose to seek a more systematic approach to define original research and guide editors to avoid it. The principles of "verifiability" and "no original research" overlap, and an attempt was made in 2007 to combine the two pages into one (see Wikipedia:Attribution), but it failed to gain consensus.
Jimmy Wales elaborated the "avoid bias" rule with a statement about "neutral point of view" in the early months of Wikipedia (within dialogue with other Wikipedians up to 12 April 2001); in subsequent versions of the NPOV policy, Jimbo's statement was known as its "original formulation".
Wikipedia:Administration – discusses both the human administrative structure of Wikipedia, as well as its non-human components.
Wikipedia:Advocacy – discusses how Wikipedia is not a venue for raising the visibility of an issue or agenda.
Wikipedia:Criticism – discusses how articles should include both positive and negative viewpoints from reliable sources, without giving undue weight to particular viewpoints, either negative or positive.
^Wikipedia's co-founder, Jimmy Wales, has described the original research policy as originating "primarily as a practical means to deal with physics cranks, of which of course there are a number on the web. The basic concept is as follows: it can be quite difficult for us to make any valid judgment as to whether a particular thing is true or not. It isn't appropriate for us to try to determine whether someone's novel theory of physics is valid, we aren't really equipped to do that. But what we can do is check whether or not it actually has been published in reputable journals or by reputable publishers. So it's quite convenient to avoid judging the credibility of things by simply sticking to things that have been judged credible by people much better equipped to decide. The exact same principle will hold true for history, though I suppose the application will in some cases be a bit different and more subtle." Wales, Jimmy. "Original research", 2004-12-03.