 | This help page is a how-to guide. It explains concepts or processes used by the Wikipedia community. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus. |
 | This page assumes you are using VisualEditor. Alternatively, learn referencing in the source editor. The source editor shows underlying wiki markup like [[Earth]]. The VisualEditor works like a word processor. |  |
![A cartoon of a political rally, with someone in the crowd holding up a banner reading "[Citation needed]"](https://wikimax.nixinova.com/wp/en/File:Webcomic_xkcd_-_Wikipedian_protester_-_English.svg)
One of the key policies of Wikipedia is that all article content has to be verifiable. This means that reliable sources must be able to support the material.
All quotations, any material whose verifiability has been challenged or is likely to be challenged, and contentious material about living persons (whether negative, positive, or neutral) must include an inline citation to a source that directly supports the material. This also means that Wikipedia is not the place for original work, archival findings that have not been published, or evidence from any source that has not been published.
If you are adding new content, it is your responsibility to add sourcing information along with it. Material provided without a source is significantly more likely to be removed from an article. Sometimes it will be tagged first with a "citation needed" template to give editors a chance to find and add sources, but some editors will simply remove it because they question its veracity.
This tutorial will show you how to add inline citations to articles, and also briefly explain what Wikipedia considers to be a reliable source.
Adding references
[edit]To insert a reference, first activate VisualEditor by clicking "edit" at the top of an article. Once the toolbar has appeared, click where you wish to insert the reference. Clicking the 
button will open up a dialog box that allows you to enter the details of your reference.
There are two simple ways to create a new reference: Fully automatic (by just inserting a web URL) or manually by filling in a template (where you add each piece of information separately).
The automatic option is the easiest. Wikipedia can often auto-format a reference citation if you just insert the website URL and click "Generate". Take a look at the citation that it then creates. To accept it, click "Insert". You can then modify the details, if VE has got something wrong, such as the publication date, by clicking "Edit".
To enter the information about a reference manually, click the "Manual" tab of the dialog box. Then you select which type of reference you want to add, and fill in as many of the fields ("parameters") as possible.
Sometimes the reference you want to add doesn't fall into any of these categories (for example, perhaps you want to cite a speech). In this case, you can enter the information fully manually using the "Basic form". (These types of references are currently easier using Wiki markup citations.)
Editing existing references
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To edit an existing reference, click on the [number] where it appears in the text. You will see either a 
"Reference icon", or the icon (and name) for the template that was used to create this reference. Clicking the "Edit" button opens a "template mini-editor" dialog where you can edit the information for that reference.
Inside the template mini-editor, you change the information in fields by typing in the boxes.
To add a new piece of information (for example, the publication date), select it in the left column.
When you're done editing the reference, click "Apply changes". Remember, you'll still need to then save your changes!
Reusing references
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Sometimes you may want to cite the same reference in multiple places on a page.
To do so, click the 
button, and select the "Re-use" tab. This will display a list of all the references currently used in the article.
To find the reference you want to re-use, either scroll through the list, or use the "Search within current citations" bar at the top. Clicking on a specific reference will insert it into the article.
Reliable sources
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Wikipedia articles require reliable, published sources that directly support the information presented in the article. Now you know how to add sources to an article, but which sources should you use?
The word "source" in Wikipedia has three meanings: the work itself (for example, a document, article, paper, or book), the creator of the work (for example, the writer), and the publisher of the work (for example, Cambridge University Press). All three can affect reliability.
Reliable sources are those with a reputation for fact-checking and accuracy. They tend to have an editorial process with multiple people scrutinizing work before it is published. Academic and peer-reviewed publications are usually the most reliable sources. Other reliable sources include university textbooks, books published by respected publishing houses, magazines, journals, and news coverage (not opinions) from mainstream newspapers.
Self-published media, where the author and publisher are the same, are usually not acceptable as sources. These can include newsletters, personal websites, press releases, patents, open wikis, personal or group blogs, and tweets. However, if an author is an established expert with a previous record of third-party publications on a topic, their self-published work may be considered reliable for that particular topic.
Whether a source is usable also depends on context. Sources that are reliable for some material are not reliable for other material. For instance, otherwise unreliable self-published sources are usually acceptable to support uncontroversial information about the source's author. You should always try to use the best possible source, particularly when writing about living people.
These are general guidelines, but the topic of reliable sources is a complicated one, and is impossible to fully cover here. You can find more information at Wikipedia:Verifiability and at Wikipedia:Reliable sources. There is also a list of commonly used sources with information on their reliability.
See also
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