- A citation is a credit or reference to another document or source. There are many rules for the format and use of such citations in different fields:
- Varying rules and practices for citations apply in a science, a law, a theological citing of authority (e.g. the isnah which "back" the hadith in Islam), the prior art that applies in patent law, or marks applied in copyright.
- Definitions of plagiarism, uniqueness or innovation, trustworthiness or reliability vary so widely among these fields that the use of citations has no simple common practice. In any of these fields the concept of a citation index can apply, which summarizes published citations of a given publication.
- When using citations, one generally uses both a works cited page or section--also called the bibliography, source list or list of references--in conjunction with parenthetical citations (citations which refer the reader to a particular cited work). Some styles use endnotes at the end of the last page or at the end of each page instead of a works cited page.
- The Modern Language Association's (MLA) style is most often used in English, foreign language, and some other humanities. MLA style uses a Works Cited Page to list works at the end of the paper. This style uses breif parenthetical citations, which include an author and page (if applicable), within the text. These direct readers to work of the author on the list of works cited, and the page of the work where the information is located (e.g. (Smith 107) refers the reader to page 107 of the work made by someone named Smith). More information can be found in the MLA Handbook for Writers of Research Papers.
- The American Psychological Association's (APA) style is most often used in social sciences. APA style lists sources at the end of the paper, on a References Page. Listing electronic sources of information is more detailed in the APA style than the MLA style. This style uses parenthetical citation within the text, listing the author's name, the year the work was made, and the page that the information may be found on. These work much like the MLA style's parenthetical citations. More information can be found in the Publication Manual of the American Psychological Association.
- Columbia Style was made by Janice R. Walker and Todd Taylor to give detailed guidelines for citing internet sources. Columbia Style offers models for both the humanities and the sciences. More information can be found in The Columbia Guide to Online Style.
A citation, in law, can also mean an official summons to appear before a court.