Wikipedia's licensing requires that attribution be given to all users involved in creating and altering the content of a page. Wikipedia's page history functionality lists all edits made to a page and all users who made these changes, but it cannot, however, in itself determine where the text originally came from. Because of this, copying content from another page within Wikipedia requires supplementary attribution to indicate it. At a minimum, this means providing an edit summary at the destination page—that is, the page into which the material is copied—stating that content was copied, together with a link to the source (copied-from) page, e.g. Copied content from [[<page name>]]; see that page's history for attribution. It is good practice, especially if copying is extensive, to make a note in an edit summary on the source page as well. Content reusers should also consider leaving notes on the talk pages of both the source and destination.

Copying and translating information from a Wikimedia project other than the English Wikipedia is usually possible, since all Wikimedia projects use the same or compatible licensing for most of their content. The edit summary must provide either a link to the original source or a list of all contributors. There are templates that may be used on the article's talk page to add supplementary information. See § Copying from other Wikimedia projects for more info.

Contributors to Wikipedia are not asked to surrender their copyright to the material they contribute. Instead, they are required to co-license their contributions under the copyleft licenses Creative Commons Attribution-ShareAlike 4.0 International License (CC BY-SA) and GNU Free Documentation License (GFDL). Both of these licenses allow reuse and modification, but reserve the right to attribution.

The CC BY-SA, section 4(c), states that:

You must ... provide ... the name of the Original Author (or pseudonym, if applicable) ... and ... in the case of an Adaptation, a credit identifying the use of the Work in the Adaptation (e.g., "French translation of the Work by Original Author," or "Screenplay based on original Work by Original Author"). The credit required by this Section 4(c) may be implemented in any reasonable manner; provided, however, that in the case of a Adaptation or Collection, at a minimum such credit will appear, if a credit for all contributing authors of the Adaptation or Collection appears, then as part of these credits and in a manner at least as prominent as the credits for the other contributing authors.

The GFDL, section 4-I, states that:

... you must ... Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page.

The Wikimedia Foundation's Terms of Use are clear that attribution will be supplied:

in any of the following fashions: a) through a hyperlink (where possible) or URL to the article or articles you contributed to, b) through a hyperlink (where possible) or URL to an alternative, stable online copy which is freely accessible, which conforms with the license, and which provides credit to the authors in a manner equivalent to the credit given on this website, or c) through a list of all authors. (Any list of authors may be filtered to exclude very small or irrelevant contributions.)

If material is used without attribution, it violates the licensing terms under which it has been provided, which in turn violates the Reusers' rights and obligations clause of Wikipedia's copyrights policy.

The correct attribution of text copied from one article to another allows editors to find easily the previous edit history of the copied text with all the advantages that access to the edit history of text contained in an article provides. Listed below are some of the advantages appropriate attribution brings that are specific to text copied from one article to another.

If a Wikipedia article (the "parent article") contains text that is a breach of third-party copyright and is copied to another article (the "child article"), then the child article will also contain a copyright violation. Attributing the copy in the child article as specified below helps editors identify when an inadvertent breach of copyright occurred and determine that the editor who made the copy did so without knowing that it was a breach of copyright. (See here for an example.) The appropriate attribution in the child article may also help editors trace the copyright violation back to the parent article.

If text with one or more short citations is copied from one or more parent articles into a child article, but the corresponding full reference in the parent's references section is not copied across, without appropriate attribution as specified below, it can be difficult to identify the full reference needed to support the short citations. (See here for an example.)

Not everything copied from one Wikipedia page to another requires attribution. If the re-user is the sole contributor of the text at the other page, attribution is not necessary. Content rewritten in one's own words does not need attribution. However, duplicating material by other contributors that is sufficiently creative to be copyrightable under US law (as the governing law for Wikipedia) requires attribution.

As guidance, none of the following require attribution when copied within Wikipedia:

• Common expressions and idioms;
• Basic mathematical and scientific formulae;
• Citations and references.

However, attributing the first two is encouraged.

Quotes from external sources do not need to be attributed to the original Wikipedia contributor, although any text surrounding them would be, and the original source must still be cited. However, even though attribution is not required in these cases, including a link is often useful.

Attribution can be provided in any of the fashions detailed in the Terms of Use (listed above), although methods (a) and (c)—i.e., through a hyperlink (where possible) or URL to the article or articles you contributed to; or through a list of all authors—are the most practical for transferring text from one Wikipedia page to another. Both methods have strengths and weaknesses, but either satisfies the licensing requirements if properly done.

If the material has been contributed by more than one author, providing a link in the edit summary is the simplest method of providing attribution. A statement in the edit summary such as copied content from [[page name]]; see that page's history for attribution will direct interested parties to the edit history of the source page, where they can trace exactly who added what content when. A disadvantage with this method is that the page history of the original article must subsequently be retained in order to maintain attribution. To avoid the source page being inadvertently moved or deleted, it is helpful to make a note of the copying on the talk page of the source article. The template {{copied}} can be used for this purpose. This template can also be added to the destination talk page.

When dealing with a page edited by many, a hyperlink is the simplest solution, but if the content being copied has only one contributor, it may be preferable simply to list that editor individually. Using this method, the edit history of the source page will be unnecessary after four years under the GFDL, though sooner deletion is possible under a CC-BY-SA 4.0 only license. A statement in the edit summary such as text from [[page name]] originally contributed by [[User:Example]] on 05 November 2024 serves as full attribution. If the material being copied has more than one author, attribution requirements can technically be satisfied with a note in the edit summary directing attention to a list of contributors on the talk page, but as the Terms of Use indicate, a hyperlink is preferred where possible. If the page where the material has been copied has to be deleted within four years, use {{CC-notice}} on the destination page with license bysa4, to notify readers that the page can no longer be distributed under the GFDL.

A dummy edit may be used to provide the edit summary attribution in either of the methods described above.

While there may be many reasons to duplicate text from one page into another, there are additional procedures, and templates, which may be necessary for certain situations of copying within Wikipedia. For merging two articles together or content from one article into another, see Wikipedia:Merging. For splitting one article into two or more, see Wikipedia:Splitting. For splitting content from one page and merging it into another page, see Wikipedia:Section move.

If copying or moving via "transwiki" from another Wikimedia project that is licensed under CC BY-SA (such as Wikimedia Commons, Wiktionary, and Wikispecies), you may satisfy attribution either by providing a complete list of authors of the original content (the complete list can be generated by copying the history of the remote page) or by providing a direct link to the original material. If the list of authors is brief, this may be provided in the edit summary. A direct link (such as an InterWikimedia link) must be included in the edit summary; the template {{Interwiki copy}} is available for the article's talk page. If leaving a list of authors, also provide a URL to the original page in case it becomes necessary in the future to access that history. (See Help:Transwiki.)

Although most Wikimedia projects are licensed under CC BY-SA and require attribution consistent with the Foundation's Terms of Use, some projects are handled differently. For example, content from Wikinews is licensed under CC BY and may be reused with attribution only to "Wikinews." (See Wikinews:Copyright.) It is the responsibility of the editor importing content to determine the license that applies and ensure that attribution is satisfied.

Translations of copyrighted text, even from other Wikimedia projects, are derivative works, and attribution must be given to satisfy licensing requirements. When translating material from a Wikimedia project licensed under CC BY-SA, a note identifying the Wikimedia project (such as an interlanguage link) and the page name must be provided. The preferred way to do this is in an edit summary in the translated page, ideally in its first edit, as in this example (using a French Wikipedia article as an example):

Content in this edit is translated from the existing French Wikipedia article at [[:fr:Exact name of French article]]; see its history for attribution.

If you forget to to do this, see #Repairing insufficient attribution below.

Where applicable, the template {{Translated page}} may also be added to the talk page to supplement copyright attribution.

There are also some situations in Wikipedia where copying may not be appropriate, such as if two articles are being created on the same subject because editors of the original cannot agree on the article's development. This is called "content forking". The acceptable solution to disagreement on the development of an article is to seek consensus through dispute resolution.

If an article is deleted, its history is removed and thus its content cannot be reused on Wikipedia—even under the same article title—unless attribution is otherwise provided (or the page undeleted). Deleted articles may not be recovered and reused from Wikipedia mirrors, online archives, or the view-deleted administrator right.

It may sometimes be necessary to delete specific parts of an article's history for various reasons (copyright violations introduced but later excised; extreme personal attacks; personal information) through Selective History deletion, Revision Deletion or Oversight. If the article retains contributions placed by users in the deleted / oversighted revisions, those must be attributed. Dummy edits should be used for this purpose, whenever practical; otherwise, talk page attribution will be necessary. A typical dummy edit summary could read, for instance Revision deletion for reason XYZ: Article was started by and retains contributions from [[User:Example]], as well as contributions from [[User:Example2]] and [[User:Example3]]

If an article is "userfied"—copied or moved into user space—it must be fully attributed. If an article is being moved to userspace to avoid deletion (or to work on after deletion), the full history should be visible (restored if necessary) and then moved using the move button. When copying all or part of an article to userspace, an edit summary like creating page with content copied from revision 123456789 of [[article title]] should be used.

While technically licensing violations are copyright violations, pages that contain unattributed text do not normally need to be deleted. Attribution can be belatedly supplied by the methods above, using dummy edits to record new edit summaries. Such belated attribution should make clear when the relevant text entered the page. You can also identify problem articles, in particular complex cases that you cannot fix right away, by tagging the article itself with the templates {{CWW}} (for a single origin) and {{CWW-multi}} (for articles with multiple origins).

For copied material, you may use an edit summary like this:

NOTE: The previous edit as of 22:31, October 14, 2015, copied content from the Wikipedia page at [[Exact name of page copied from]]; see its history for attribution.

For translated material, an edit summary like this:

NOTE: Content in the edit of 01:25, January 25, 2023 was translated from the existing French Wikipedia article at [[:fr:Exact name of French article]]; see its history for attribution.

Suggestions for various other repair contexts are provided at Help:Dummy edit.

The template {{Unattributed translation}} is available to tag an article as needing attribution. When possible, the re-user should be notified of the proper procedures for copying and translating text between pages. The {{uw-copying}} and {{uw-translation}} templates can be used to notify a user. The template {{uw-c&pmove}} is available for addressing cut-and-paste moves.

If the entire contents of one page were relocated to another title via cutting and pasting, leaving a redirect at the previous page, the licensing violation can be repaired through the use of the {{history merge}} template. If the situation is more complex—for example, if a new article has developed at the source page on a subject with related title—the situation should be listed at Wikipedia:Requests for history merge for administrator attention.

Transclusion is an alternative for avoiding duplicating content by copying and pasting within Wikipedia. Automatic excerpts can help specially in following summary style. (See also: using excerpts for article synchronization.)

• Wikipedia:User pages § Content copied from mainspace
• Wikipedia:Copying text from other sources
• Wikipedia:Adding open license text to Wikipedia
• {{Circular}}