Wikipedia:Reliable sources

The verifiability policy is strictly applied to all material in the mainspace—articles, lists, and sections of articles—without exception, and in particular to biographies of living persons, which states: Contentious material about living persons (or, in some cases, recently deceased) that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—must be removed immediately and without waiting for discussion.In the event of a contradiction between this guideline and our policies regarding sourcing and attribution, the policies take priority and editors should seek to resolve the discrepancy.

This means that we publish only the analysis, views, and opinions of reliable authors, and not those of Wikipedians, who have read and interpreted primary source material for themselves.

Proper sourcing always depends on context; common sense and editorial judgment are an indispensable part of the process.

In general, the more people engaged in checking facts, analyzing legal issues, and scrutinizing the writing, the more reliable the publication.

Especially in scientific and academic fields, older sources may be inaccurate because new information has been brought to light, new theories proposed, or vocabulary changed.

If outside citation is the main indicator of reliability, particular care should be taken to adhere to other guidelines and policies, and to not unduly represent contentious or minority claims.

However, some scholarly material may be outdated, in competition with alternative theories, controversial within the relevant field, or largely ignored by the mainstream academic discourse because of lack of citations.

Reliable non-academic sources may also be used in articles about scholarly issues, particularly material from high-quality mainstream publications.

Bias may make in-text attribution appropriate, as in "The feminist Betty Friedan wrote that..."; "According to the Marxist economist Harry Magdoff..."; or "The conservative Republican presidential candidate Barry Goldwater believed that...".

Such sources include websites and publications expressing views that are widely acknowledged as extremist, that are promotional in nature, or that rely heavily on rumors and personal opinions.

Indications that an article was published in a supplement may be fairly subtle; for instance, a letter "S" added to a page number,[15] or "Suppl."

However, groups that do have a COI may hide behind layers of front organizations with innocuous names, so the ultimate funding sources should always be ascertained.

Sites with user-generated content include personal websites, personal and group blogs (excluding newspaper and magazine blogs), content farms, Internet forums, social media sites, fansites, video and image hosting services, most wikis and other collaboratively created websites.

Examples of unacceptable user-generated sources are Ancestry.com, Discogs, Facebook, Famous Birthdays, Fandom, Find a Grave, Goodreads, IMDb, Instagram, Know Your Meme, Reddit, Snapchat, TikTok, Tumblr, TV Tropes, Twitter, WhoSampled, and Wikipedia (self referencing).

Use of self-sourced material should be de minimis; the great majority of any article must be drawn from independent sources.

LLMs also have a tendency to "hallucinate" false information, including source citations that look as if they are from reputable publications but do not actually exist.

Contentious material about a living person that is unsourced or poorly sourced should be removed immediately; do not move it to the talk page.

Wikipedia articles should be based mainly on reliable secondary sources, i.e., a document or recording that relates to or discusses information originally presented elsewhere.

Ideal sources for biomedical information include general or systematic reviews in reliable, independent, published sources, such as reputable medical journals, widely recognised standard textbooks written by experts in a field, or medical guidelines and position statements from nationally or internationally reputable expert bodies.

It is vital that the biomedical information in all types of articles be based on reliable, independent, published sources and accurately reflect current medical knowledge.

For example, the Moon landing conspiracy theories article may include material from reliable websites, movies, television specials, and books that are not peer-reviewed.

By parity of sources, critiques of that material can likewise be gleaned from reliable websites and books that are not peer-reviewed.

Of course, for any viewpoint described in an article, only reliable sources should be used; Wikipedia's verifiability and biographies of living persons policies are not suspended simply because the topic is a fringe theory.

Editors should avoid original research especially with regard to making blanket statements based on novel syntheses of disparate material.

Stated simply, any statement in Wikipedia that academic consensus exists on a topic must be sourced rather than being based on the opinion or assessment of editors.

This gives journalists time to collect more information and verify claims, and for investigative authorities to make official announcements.

The On the Media Breaking News Consumer's Handbook[19] contains several suggestions to avoid spreading unreliable and false information.

With mass shootings, remain skeptical of early reports of additional attackers, coordinated plans, and bomb threats.

On the Media cautions consumers to be wary of news reports describing early science and medical breakthroughs,[20] especially those which do not interview independent experts (often solely based on unreliable press releases), to prefer reports which avoid hyperbolic language and describe both benefits and costs of a new treatment (all treatments have trade-offs), to be wary of disease mongering (exaggerating risks, symptoms, or anecdotes of a disease which leads to unnecessary worry, panic, or spending), and to be skeptical of treatments which are "awaiting FDA approval" or in pre-clinical testing" as more than 90% of all treatments fail during these stages and,[21] even if efficacious, may be 10 to 15 years or more from reaching the consumer market.

Blacklisting is generally reserved for sources which are added abusively, such as state-sponsored fake news sites with a history of addition by troll farms.