Stock car racing:Verifiability

Much of the information on is derived from published sources. Some of the information on has been produced by scholarly research performed at. Sources of information should be cited in order to allow others to find the sources and judge their reliability. If a cited source can be checked, the information is verifiable. Facts, viewpoints, theories, and arguments can be included at if verifiable sources are cited. Information on pages that is not supported by verifiable sources can be challenged and removed to talk pages for discussion.

The threshold for inclusion of information on pages is verifiability, not truth. Verifiable in this context means that any reader must be able to check that material added to pages has either:
 * 1) already been published by a reliable source; or
 * 2) has been produced by scholarly research performed at.

Verifiability is one of 's main content-guiding policies. Another is Reliable sources. These policies should not be interpreted in isolation from one another, and editors should therefore try to familiarize themselves with both. The obligation to use verifiable and reliable sources lies with the editors wishing to include information on a page, not on those seeking to question it or remove it.

Verifiability, not truth
"Verifiability" in this context does not mean that editors are expected to verify whether, for example, the contents of a reliable journal article are true. A good way to look at the distinction between verifiability and truth is with the following example. Suppose you are learning about a famous physicist's Theory X, which has been published in peer-reviewed journals and is therefore appropriate content for study at Wikiversity. However, if you happen to know the physicist and he tells you, "Actually, I now believe Theory X to be completely false," it has been claimed (see the history of this page) that "you cannot include the fact that he said it in a Wikiversity page. Why not? Because what he said to you is not verifiable by other  editors."

It is routine in peer-reviewed publications that alleged fact is cited to "conversations with So-and-so." The fact reported is the conversation, not truth. And the author of the paper is the witness. Hence such alleged facts require attribution, not only to the alleged source (the physicist above) but also to the witness.

It is not generally true that "private conversation" is unverifiable. One may write to the "famous physicist" and ask, if he or she is still alive. Otherwise, the basic common-law principle is that testimony is presumed true unless controverted. allows original research, and this is an aspect of it. Original research must be, and certainly if challenged, attributed to the researcher. While page history will show who added original research, this should be explicit in the text or context. On top-level mainspace pages, these rules may be relatively strict. In subpages, subpages may be, in toto, attributed to author or other user, in which case they should normally not be edited by others without permission.

Copyright and plagiarism
Do not plagiarize or breach copyright when using sources. Summarize source material in your own words as much as possible; when quoting or closely paraphrasing a source use an inline citation, and in-text attribution where appropriate.

Do not link to any source that violates the copyrights of others per contributors' rights and obligations. You can link to websites that display copyrighted works as long as the website has licensed the work, or uses the work in a way compliant with fair use. Knowingly directing others to material that violates copyright may be considered contributory copyright infringement. If there is reason to think a source violates copyright, do not cite it. This is particularly relevant when linking to sites such as Scribd or YouTube, where due care should be taken to avoid linking to material that violates copyright.

Neutrality
Even when information is cited to reliable sources, you must present it with a neutral point of view (NPOV). Articles should be based on thorough research of sources. All articles must adhere to NPOV, fairly representing all majority and significant-minority viewpoints published by reliable sources, in rough proportion to the prominence of each view. Tiny-minority views need not be included, except in articles devoted to them. If there is disagreement between sources, use in-text attribution: "John Smith argues X, while Paul Jones maintains Y," followed by an inline citation. Sources themselves do not need to maintain a neutral point of view. Indeed, many reliable sources are not neutral. Our job as editors is simply to summarize what the reliable sources say.

Notability
If no reliable, independent sources can be found on a topic, should not have an article on it (i.e., the topic is not notable).

Original research
The no original research policy (NOR) is closely related to the Verifiability policy. Among its requirements are:
 * 1) All material in  articles must be attributable to a reliable published source. This means a reliable published source must exist for it, whether or not it is cited in the article.
 * 2) Sources must support the material clearly and directly: drawing inferences from multiple sources to advance a novel position is prohibited by the NOR policy.
 * 3) Base articles largely on reliable secondary sources. While primary sources are appropriate in some cases, relying on them can be problematic. For more information, see the Primary, secondary, and tertiary sources section of the NOR policy, and the Misuse of primary sources section of the BLP policy.