Editing Encyclopedia:Citing sources (section)

===Preventing and repairing dead links <span id="Dead links"></span>===
{{see also|Wikipedia:Link rot|Help:Archiving a source}}
{{Shortcut|WP:DEADREF}}

To help prevent [[Wikipedia:Dead external links|dead links]], persistent identifiers are available for some sources. Some journal articles have a [[digital object identifier]] (DOI); some online newspapers and blogs, and also Wikipedia, have [[permalink]]s that are stable. When permanent links aren't available, consider making an archived copy of the cited document when writing the article; on-demand web archiving services such as the [[Wayback Machine]] (https://web.archive.org/save) or [[archive.today]] (https://archive.today) are fairly easy to use (see [[Wikipedia:Citing sources/Further considerations#Pre-emptive archiving|pre-emptive archiving]]).

'''Do not delete a citation merely because the URL is not working'''. Dead links should be repaired or replaced if possible. If you encounter a dead URL being used as a reliable source to support article content, follow these steps prior to deleting it:

# '''Confirm status''': First, check the link to confirm that it is dead and not temporarily down. Search the website to see whether it has been rearranged. The online service [https://www.isitdownrightnow.com/ "Is it down right now?"] can help to determine if a ''site'' is down, and any information known.
# '''Check for a changed URL on the same website''': Pages are frequently moved to different locations on the same site as they become archive content rather than news. The site's error page may have a "Search" box; alternatively, in both the Google and DuckDuckGo search engines – among others – the keyterm "site:" can be used. For instance: <code>site:nytimes.com "the goose is loose"</code>.
# '''Check for web archives''': Many [[web archiving]] services exist (for a full list, see: [[Wikipedia:List of web archives on Wikipedia]]); link to their archive of the URL's content, if available. Examples:
#* [[Internet Archive]] has billions of archived web pages. See [[Wikipedia:Using the Wayback Machine]].
#* [[archive.today]] See [[Wikipedia:Using archive.today]]
#* The [[UK Government Web Archive]] (https://www.nationalarchives.gov.uk/webarchive/) preserves 1500 UK central government websites.
::If multiple archive dates are available, try to use one that is most likely to be the contents of the page seen by the editor who entered the reference on the {{para|access-date}}. If that parameter is not specified, a [http://wikipedia.ramselehof.de/wikiblame.php?lang=en search of the article's revision history] can be performed to determine when the link was added to the article.
::For most citation templates, archive locations are entered using the {{para|archive-url}}, {{para|archive-date}} and {{para|url-status}} parameters. The primary link is switched to the archive link when {{para|url-status|dead}}. This retains the original link location for reference.
::If the web page now leads to a completely different website, set {{para|url-status|usurped}} to hide the original website link in the citation.
::''Note:'' Some archives currently operate with a delay of ~18 months before a link is made public. As a result, editors should wait ~24 months after the link is first tagged as dead before declaring that no web archive exists. Dead URLs to reliable sources should normally be tagged with {{Tlx|dead link|date{{=}}{{CURRENTMONTHNAME}} {{CURRENTYEAR}}}}, so that you can estimate how long the link has been dead.
::'''Bookmarklets''' to check common archive sites for archives of the current page:
::;Archive.org: <syntaxhighlight lang="javascript" inline>javascript:void(window.open('https://web.archive.org/web/*/'+location.href))</syntaxhighlight>
::;archive.today / archive.is: <syntaxhighlight lang="javascript" inline>javascript:void(window.open('https://archive.today/'+location.href))</syntaxhighlight>
::;Mementos interface: <syntaxhighlight lang="javascript" inline>javascript:void(window.open('https://www.webarchive.org.uk/mementos/search/'+encodeURIComponent(location.href)+'?referrer='+encodeURIComponent(document.referrer)))</syntaxhighlight>
# <li value="4">'''Remove convenience links''': If the material was published on paper (e.g., academic journal, newspaper article, magazine, book), then the dead URL is not necessary. Simply remove the dead URL, leaving the remainder of the reference intact.</li>
# '''Find a replacement source''': Search the web for quoted text, the article title, and parts of the URL. Consider contacting the website/person that originally published the reference and asking them to republish it. Ask other editors for help finding the reference somewhere else, including the user who added the reference. Find a different source that says essentially the same thing as the reference in question.
# '''Remove hopelessly-lost web-only sources''': If the source material does not exist offline, {{em|and}} if there is no archived version of the web page (be sure to wait ~24 months), {{em|and}} if you cannot find another copy of the material, then the dead citation should be removed and the material it supports should be regarded as unverified if there is no other supporting citation. If it is material that is [[WP:MINREF|specifically required by policy to have an inline citation]], then please consider tagging it with {{tlx|citation needed}}. It may be appropriate for you to move the citation to the talk page with an explanation, and notify the editor who added the now-dead link.