Wikipedia:Use of primary sources in Wikipedia

Most often, primary sources used in Wikipedia are a form of illustration. They illustrate what reliable secondary and tertiary sources learn about the discussed topic. Illustrations are a valid part of any encyclopedia, but should not outdo the content based on secondary or tertiary sources.

Definitions and scope
A primary source is a document or person providing direct evidence of a certain state of affairs; in other words, a source very close to the situation you are writing about. The term most often refers to a document produced by a participant in an event or an observer of that event. It could be an official report, a letter, an eyewitness account, an autobiography, or statistics compiled by an authoritative agency.

Types of primary sources
Primary sources present information or data, such as:
 * archeological artifacts
 * photographs
 * historical documents such as a diary, census, video or transcript of surveillance, a public hearing, trial, or interviews
 * tabulated results of surveys or questionnaires
 * written or recorded records of laboratory assays or observations
 * written or recorded records of field observations
 * artistic and fictional works such as poems, scripts, screenplays, novels, motion pictures, videos, and television programs

Note that primary sources make no exception to the general rules regarding sources (WP:V, WP:RS, WP:NOR,...) before they can be used as a source in Wikipedia. That are basic requirements, not further discussed in, nor modified by, the current guideline (proposal). This guideline concentrates on how to use primary sources most appropriately in Wikipedia.

For instance, a published official court transcript of witness evidence would pass the minimum criteria of reliability for use as a source in Wikipedia. Quotes from such sources can be used to illustrate the position or perspective of the witness. The transcript (while it is a primary source) can not be used as a basis to present the slant (opinion, perspective, position, observations...) of the witness as "fact". That is, unless a reliable secondary or tertiary source (for instance a judge's verdict, or a generally accepted history book written after conclusion of the court case) does so.

This guideline also does not distinguish between primary and secondary (or tertiary) sources as a reliability criterion. Sometimes an eye witness report can be much more reliable than a newspaper article describing what the eye witness allegedly saw. Or the other way around, a peer reviewed scientific analysis can sometimes prove that what the eye witness saw was an optical illusion. The scope of this guideline is not making distinctions between the various levels of "truth" of sources, depending on type. The scope of this guideline is rather giving style recommendations on how to present sources. For that style guidance, there's a value in distinguishing between types of sources.

Primary sources by use
In some circumstances any source becomes a primary source:

Sources in articles about themselves
If you're writing an article about a person or about an object (book, recording,...) the main topic of that article is always a primary source with regard to that article.

For instance, Bertrand Russell's History of Western Philosophy is generally a secondary source (maybe even a tertiary source) describing the development of Western philosophy. In that quality it can, for instance, be used in the Wikipedia article on Plato's Republic. But in the Wikipedia article "History of Western Philosophy (Russell)", Russell's book can only be treated as a primary source with regard to that Wikipedia article.

Similarly, autobiographies, even if (for instance) they could sometimes be secondary sources on some historical developments in public life described by the author, they'd always be exclusively "primary" source in the Wikipedia article on the author of that autobiography.

Direct quotes from secondary sources
Normally there's no need to give a direct quote of whatever secondary source used as a basis for a Wikipedia article. When, for a specific reason (often, for instance, a problem of interpretation), a direct quote is needed, the quote quite unavoidably becomes a primary source.

For example, there are several biographies of Johann Sebastian Bach. Wikipedia's article on Bach doesn't need direct quotes of his major biographers. In Bach's article the known facts about his life are summarized, with references to the standard biographies. The article on one of Bach's compositions, the Goldberg Variations, has however a large quote of Bach's first biographer (Forkel). The reason is that Forkel's account of the history of this composition has several historical exactitude issues. It is a primary source on the Keyserling/Goldberg story (legend?) regarding the composition.

Note that for large quotes from tertiary sources the same conversion to primary source usually does not occur. For instance, many Wikipedia articles started out as a copy-paste job from 1911 Britannica. None of these quotes have a "primary source" characteristic. On the other hand, quoting a tertiary source in the format of a primary source quote should generally be avoided.

Broader concept of illustration
Illustrations can be images, other media (music, video) and quotes. Most of these are primary sources.

A good article usually has some illustrations (compare: What is a featured article?), in the form of images and/or audio files and/or video fragments and/or relevant quotes.

Also off-site reading, viewing or listening suggestions and Media examples indicated in a Wikipedia article are rather a part of the "illustration" of the topic, than the basis for its verifiability.

Difference with "decorative purpose"
From Fair use (criteria No. 8):"The material must contribute significantly to the article (e.g. identify the subject of an article, or specifically illustrate relevant points or sections within the text) and must not serve a purely decorative purpose."Although this is only binding for copyrighted insertions used under a "fair use" doctrine, the recommendation not to err towards decorative use of illustrations can be taken into account everywere. Compare Wikipedia is not a mirror or a repository of links, images, or media files.

Don't overdo it
General principle: no "illustration" without treating the illustrated topic on the basis of secondary and/or tertiary sources. In other words, (links to) illustrations that are not covered by attributable descriptions have no place in Wikipedia.

Also, Wikipedia is not a link repository. In general, when there's more "illustration" than actual content covered by an article, such article is fundamentally out of balance.

In general, Don't include copies of primary sources in Wikipedia articles: use sister projects (,, ,...) for the copies of the primary sources (where not restricted by copyright, see next paragraph), and link to these sister projects instead of including the full primary sources in Wikipedia. In general, this comes down to having a limited and carefully chosen set of text extracts, images, and other illustrations in any Wikipedia article.

Other limitations regarding the use of illustrations (or: primary sources) in Wikipedia are copyright-related: there are limitations both for sources copied to Wikimedia projects, as for external links to possibly copyright-infringing sources.

Exceptions
Apart that any illustration should of course be referenced to its origin (whether or not that "origin" is generally described as a primary source), there are only limited exceptions where verification of Wikipedia content relies on primary rather than on secondary or tertiary sources:

Current events
Temporary use of primary sources as a basis for descriptions of current events is an under certain circumstances allowable exception indicated by ArbCom (Requests for arbitration/Israel-Lebanon).

Important: by the time the event is no longer current, no primary sources should be used for verification of the article content any more: (links to) primary sources should either have been replaced by links to secondary sources discussing such topics, or be accepted as part of a limited set of illustrations to such article.

Summaries and descriptions of primary sources in articles about themselves
Any source is a primary source with regard to the Wikipedia article having that source as main topic (see above ). A summary of the content (or the "plot") of such primary source can of course be based on that "primary" source itself. Similarly, no "secondary" or "tertiary" source is needed to describe the colour of the [[media:Chameleon - Tanzania - Usambara Mountains.jpg|chameleon on this image]]. Sometimes such summaries or descriptions are based on summaries or descriptions found in secondary or tertiary sources too, in which case such accessory sources should be mentioned in the Wikipedia article. However, in general there's no problem with producing a straightforward (i.e. not disturbed by subjective interpretation) summary or description of a primary source based on that source itself, in its own article.

So, for instance, if a novel is notable enough to be included in Wikipedia in a separate article, such article would usually give a plot summary of that novel. In most cases such plot summaries are derived from the novel itself.

Similarly, autobiographies are sometimes used as the basis for articles on their authors. Even if the autobiographical material is doubted by secondary sources, the primary material can sometimes be summarized as part of the description of the difference with the secondary source narrative.

Proposed categorisations: Category:Wikipedia proportion and emphasis (subcategory of Category:Wikipedia content), and Category:Wikipedia style guidelines