|This page in a nutshell: 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 reach or imply a conclusion not clearly stated by the sources themselves.|
Wikipedia articles must not contain original research. The phrase "original research" (OR) is used on Wikipedia to refer to material—such as facts, allegations, and ideas—for which no reliable, published sources exist.[a] This includes any analysis or synthesis of published material that serves to reach or imply a conclusion not stated by the sources. To demonstrate that you are not adding original research, you must be able to cite reliable, published sources that are directly related to the topic of the article, and directly support the material being presented. (This policy of no original research does not apply to talk pages and other pages which evaluate article content and sources, such as deletion discussions or policy noticeboards.)
The prohibition against original research means that all material added to articles must be attributable to a reliable, published source, even if not actually attributed.[a] The verifiability policy says that an inline citation to a reliable source must be provided for all quotations, and for anything challenged or likely to be challenged—but a source must exist even for material that is never challenged. For example, the statement "the capital of France is Paris" needs no source, nor is it original research, because it's not something you thought up and is easily verifiable; therefore, no one is likely to object to it and we know that sources exist for it even if they are not cited. The statement is attributable, even if not attributed.
Despite the need for reliable sources, you must not plagiarize them or violate their copyrights. Rewriting source material in your own words while retaining the substance is not considered original research.
"No original research" (NOR) is one of three core content policies that, along with Neutral point of view and Verifiability, determines the type and quality of material acceptable in articles. Because these policies work in harmony, they should not be interpreted in isolation from one another, and ors should familiarize themselves with all three. For questions about whether any particular constitutes original research, see the No original research noticeboard.
Wikipedia is fundamentally built on research that has been collected and organized from reliable sources, as described in content policies such as this one. If no reliable independent sources can be found on a topic, Wikipedia should not have an article about it. If you discover something new, Wikipedia is not the place to announce such a discovery.
The best practice is to research the most reliable sources on the topic and summarize what they say in your own words, with each statement in the article attributable to a source that makes that statement explicitly. Source material should be carefully summarized or rephrased without changing its meaning or implication. Take care not to go beyond what the sources express or to use them in ways inconsistent with the intention of the source, such as using material out of context. In short, stick to the sources.
Any material challenged or likely to be challenged must be supported by a reliable source. Material for which no reliable source can be found is considered original research. The only way you can show your is not original research is to cite a reliable published source that contains the same material. Even with well-sourced material, if you use it out of context, or to reach or imply a conclusion not directly and explicitly supported by the source, you are engaging in original research; see below.
In general, the most reliable sources are:
As a rule of thumb, the more people engaged in checking facts, analyzing legal issues, and scrutinizing the writing, the more reliable the publication. Self-published material, whether on paper or online, is generally not regarded as reliable. See self-published sources for exceptions.
Information in an article must be verifiable in the references cited. In general, article statements should not rely on unclear or inconsistent passages or on passing comments. Any passages open to multiple interpretations should be precisely cited or avoided. A summary of extensive discussion should reflect the conclusions of the source. Drawing conclusions not evident in the reference is original research regardless of the type of source. References must be cited in context and on topic.
Wikipedia articles should be based on reliable, published secondary sources and, to a lesser extent, on tertiary sources and primary sources. Secondary or tertiary sources are needed to establish the topic's notability and avoid novel interpretations of primary sources. All analyses and interpretive or synthetic claims about primary sources must be referenced to a secondary or tertiary source and must not be an original analysis of the primary-source material by Wikipedia ors.
Appropriate sourcing can be a complicated issue, and these are general rules. Deciding whether primary, secondary, or tertiary sources are appropriate in any given instance is a matter of good orial judgment and common sense, and should be discussed on article talk pages. A source may be considered primary for one statement but secondary for a different one. Even a given source can contain both primary and secondary source material for one particular statement. For the purposes of this policy, primary, secondary and tertiary sources are defined as follows:[b]
Do not combine material from multiple sources to reach or imply a conclusion not explicitly stated by any source. Similarly, do not combine different parts of one source to reach or imply a conclusion not explicitly stated by the source. If one reliable source says A and another reliable source says B, do not join A and B together to imply a conclusion C not mentioned by either of the sources. This would be improper orial synthesis of published material to imply a new conclusion, which is original research performed by an or here.[i] "A and B, therefore, C" is acceptable only if a reliable source has published the same argument concerning the topic of the article. If a single source says "A" in one context, and "B" in another, without connecting them, and does not provide an argument of "therefore C", then "therefore C" cannot be used in any article.
Here are two sentences showing simple examples of improper orial synthesis. Both halves of the first sentence may be reliably sourced but are combined to imply that the UN has failed to maintain world peace. If no reliable source has combined the material in this way, it is original research.
The United Nations' stated objective is to maintain international peace and security, but since its creation there have been 160 wars throughout the world.
In this second sentence, the opposite is implied using the same material, illustrating how easily such material can be manipulated when the sources are not adhered to:
The United Nations' stated objective is to maintain international peace and security, and since its creation there have been only 160 wars throughout the world.
Here are two paragraphs showing more complex examples of orial synthesis. They are based on an actual Wikipedia article about a dispute between two authors, here called Smith and Jones. This first paragraph is fine because each of the sentences is carefully sourced, using a source that refers to the same dispute:
Smith stated that Jones committed plagiarism by copying references from another author's book. Jones responded that it is acceptable scholarly practice to use other people's books to find new references.
This second paragraph demonstrates improper orial synthesis:
If Jones did not consult the original sources, this would be contrary to the practice recommended in the Harvard Writing with Sources manual, which requires citation of the source actually consulted. The Harvard manual does not call violating this rule "plagiarism". Instead, plagiarism is defined as using a source's information, ideas, words, or structure without citing them.
The second paragraph is original research because it expresses a Wikipedia or's opinion that, given the Harvard manual's definition of plagiarism, Jones did not commit it. Making the second paragraph policy-compliant would require a reliable source specifically commenting on the Smith and Jones dispute and makes the same point about the Harvard manual and plagiarism. In other words, that precise analysis must have been published by a reliable source concerning the topic before it can be published on Wikipedia.
Because of copyright laws in several countries, there are relatively few images available for use on Wikipedia. Editors are therefore encouraged to upload their own images, releasing them under appropriate Creative Commons licenses or other free licenses. Original images created by a Wikipedian are not considered original research, so long as they do not illustrate or introduce unpublished ideas or arguments, the core reason behind the "No original research" policy. Image captions are subject to this policy no less than statements in the body of the article.
It is not acceptable for an or to use photo manipulation to distort the facts or position illustrated by an image. Manipulated images should be prominently noted as such. Any manipulated image where the encyclopedic value is materially affected should be posted to Wikipedia:Files for discussion. Images of living persons must not present the subject in a false or disparaging light.
Faithfully translating sourced material into English, or transcribing spoken words from audio or video sources, is not considered original research. For information on how to handle sources that require translation, see WP:Verifiability § Non-English sources.
Routine calculations do not count as original research, provided there is consensus among ors that the result of the calculation is correct, and a meaningful reflection of the sources. Basic arithmetic, such as adding numbers, converting units, or calculating a person's age, is almost always permissible. See also Category:Conversion templates.
Mathematical literacy may be necessary to follow a "routine" calculation, particularly for articles on mathematics or in the hard sciences. In some cases, ors may show their work in a footnote.
Comparisons of statistics present particular difficulties. Editors should not compare statistics from sources that use different methodologies.
Wikipedia's content is determined by previously published information rather than by the personal beliefs or experiences of its ors. Even if you're sure something is true, it must be verifiable before you can add it. The policy says that all challenged or likely to be challenged material and all quotations need a reliable source; what counts as a reliable source is described at WP:Verifiability § Reliable sources.
The prohibition against original research limits the extent to which ors may present their own points of view in articles. By reinforcing the importance of including verifiable research produced by others, this policy promotes the inclusion of multiple points of view. Consequently, this policy reinforces our neutrality policy. In many cases, there are multiple established views of any given topic. In such cases, no single position, no matter how well researched, is authoritative. It is not the responsibility of any individual or to research all points of view. But when incorporating research into an article, ors must provide context for this point of view by indicating how prevalent the position is and whether it is held by a majority or minority.
The inclusion of a view that is held by only a tiny minority may constitute original research. Jimbo Wales has said of this: