Base articles on reliable, third-party, published sources with a reputation for fact-checking and accuracy. Source material must have been published, the definition of which for our purposes is "made available to the public in some form".Unpublished materials are not considered reliable. Use sources that directly support the material presented in an article and are appropriate to the claims made. The appropriateness of any source depends on the context. The best sources have a professional structure in place for checking or analyzing facts, legal issues, evidence, and arguments. The greater the degree of scrutiny given to these issues, the more reliable the source. Be especially careful when sourcing content related to living people or medicine.
If available, academic and peer-reviewed publications are usually the most reliable sources, such as in history, medicine, and science.
Editors may also use material from reliable non-academic sources, particularly if it appears in respected mainstream publications. Other reliable sources include:
Several newspapers, magazines, and other news organizations host columns on their web sites that they call blogs. These may be acceptable sources if the writers are professionals, but use them with caution because the blog may not be subject to the news organization's normal fact-checking process. If a news organization publishes an opinion piece in a blog, attribute the statement to the writer (e.g. "Jane Smith wrote..."). Never use as sources the blog comments that are left by readers. For personal or group blogs that are not reliable sources, see Self-published sources below.
To discuss the reliability of a specific source for a particular statement, consult the reliable sources noticeboard, which seeks to apply this policy to particular cases. For a guideline discussing the reliability of particular types of sources, see Wikipedia:Identifying reliable sources (WP:IRS). In the case of inconsistency between this policy and the WP:IRS guideline, or any other guideline related to sourcing, this policy has priority.