 | 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 help page is an overview and gives concise examples of several systems. Please refer to the linked main articles for details. For a more general introduction see Help:Introduction to referencing or Help:Referencing for beginners with citation templates. |
Wikipedia uses various referencing systems to cite sources that support assertions in the article and to add explanatory and supplementary material. This page compares two systems that are currently used (Footnotes and Shortened footnotes) and two older systems that are deprecated and no longer used for new articles (Footnote3 and Parenthetical referencing).