This template is used in articles to identify sentences or short passages with information or analysis that has a citation to insufficiently reliable source because the source has been surpassed by a newer edition, a followup article, a widely accepted rebuttal, a retraction, or some other advance in knowledge. It produces a superscripted notation like the following:
You can also include a |reason= note, which displays as a tooltip upon mouse hover, to leave a better record for future editors. For example, the following usage might be appropriate when later sources indicate a taxonomic change:
.svg/1280px-Test_Template_Info-Icon_-_Version_(2).svg.png){kind=icon}
{{Obsolete source|reason=This source is from 1995, but this entire fungal family was taxonomically reorganized in 2000–2001|date=September 2024}}Please check that your given |reason= renders as a tooltip as intended. For instance, if you include a " character, it cuts the tooltip short.
General template for copy-pasting:
{{Obsolete source|reason=|date=September 2024}}Adding this template to an article places the article into Category:All articles lacking reliable references (and its dated equivalent), part of a family of categories identifying articles with reliable-sourcing issues. To find all such articles, see Category:Wikipedia articles with sourcing issues.
Note that not all citations to material that is obsolete in some contexts is citation to obsolete material in every context. For example, in an article section on changes in standardized writing style, it is perfectly reasonable to cite a 1950s edition of a style and grammar guide for what its rule was on a particular matter in that era, even if its present edition recommends something completely different.
Contentious material about living persons that is unsourced or poorly sourced should be removed immediately. Do not tag it: remove it. For more information, see the section on contentious material in the Biography of Living Persons policy.
Material which is doubtful and harmful may be removed immediately, rather than tagged. See Unsourced material.
If the source is unreliable for a reason other than obsolescence, use {{Better source}} instead. If no citation is given, use {{Citation needed}}. If the source given is self-published, use {{Self-published inline}}. If you think the author has a conflict of interest or is otherwise too close to the subject, use {{Third-party inline}}.
If you have the time and ability to find a better reference, please do so. Then correct the citation yourself, or correct the article text. After all, the ultimate goal is not to merely identify problems, but to fix them.