Citation Styles: The Complete List

Citation styles are standardised rule sets that tell you how to format in-text citations and reference lists. Each discipline favours particular styles – APA for psychology, MLA for humanities, IEEE for engineering – so your assignment or journal usually dictates the choice.

What is a citation style?

A citation style is a documented set of rules governing how sources appear in a piece of academic writing. It fixes two things: the brief in-text citation that flags a borrowed idea, and the full reference entry that lets a reader find the source. Styles differ in punctuation, author order, capitalisation, italics and the placement of dates.

Most styles are maintained by a scholarly body or publisher and revised every few years – so the edition matters as much as the name. Using APA 6th rules in an APA 7th paper produces errors, even though both say “APA”.

The complete list of citation styles

There are thousands of journal-specific variants, but roughly a dozen named styles cover almost all coursework and publishing. The table lists each with its governing edition and typical field.

The four styles you will meet most

APA, MLA, Chicago and IEEE account for the overwhelming majority of student citations. Each handles the in-text pointer and the end entry differently, as the examples show.

APA (7th edition)

APA uses an author-date in-text citation and a “References” list. Titles use sentence case; only the first author is inverted-last-first in short works, and up to 20 authors are named in the reference.

In-text(Grady et al., 2019, p. 210)

ReferenceGrady, J. S., Her, M., Moreno, G., Perez, C., & Yelinek, J. (2019). Emotions in storybooks: A comparison of storybooks that represent ethnic and racial groups in the United States. Psychology of Popular Media Culture, 8(3), 207-217. https://doi.org/10.1037/ppm0000185

MLA (9th edition)

MLA pairs an author-page in-text citation with a “Works Cited” list built from the container system. Titles use title case and there is no date in the parenthetical.

In-text(Kincaid 112)

Works CitedKincaid, Jamaica. “In History.” Callaloo, vol. 24, no. 2, 2001, pp. 620-626.

Chicago (18th edition)

Chicago offers two systems. Notes-bibliography uses numbered footnotes plus a bibliography; author-date mirrors APA. The example shows a bibliography entry.

Footnote1. Zadie Smith, Swing Time (New York: Penguin Press, 2016), 315-16.

BibliographySmith, Zadie. Swing Time. New York: Penguin Press, 2016.

IEEE

IEEE uses a bracketed number in the text that matches a numbered reference list ordered by first appearance. The number, not the author, does the pointing.

In-text…as shown in [1].

Reference[1] G. Eason, B. Noble, and I. N. Sneddon, “On certain integrals of Lipschitz-Hankel type,” Phil. Trans. Roy. Soc. London, vol. 247, no. 935, pp. 529-551, Apr. 1955.

Author-date vs numbered systems

Every style belongs to one of two families, and knowing which one saves confusion. Author-date styles put a name and year in the text; numbered styles put a figure that keys to an ordered list.

• Author-date (APA, Harvard, MLA, ASA, Chicago author-date): the reader recognises sources by name at a glance, and the reference list is alphabetised by author surname.
• Numbered (IEEE, Vancouver, AMA): the text stays uncluttered, references appear in citation order, and each source keeps its number wherever it recurs. Vancouver and AMA use the same number throughout; AMA sets it in superscript, IEEE in square brackets.
• Notes (Chicago notes-bibliography, Bluebook, OSCOLA): a superscript number sends the reader to a foot- or endnote holding the full citation, with an optional bibliography as well.

How do I choose the right style?

You rarely choose freely – the decision is usually made for you. Check these sources in order before defaulting to anything.

1. Your assignment brief or module handbook. A named style there is binding; ignore general advice that contradicts it.
2. The target journal’s author guidelines, if you are submitting for publication. Many journals use a house variant.
3. Your discipline’s convention (see the table above) when nothing else specifies one.

Whatever you pick, apply one edition of one style consistently across the whole document. Mixing APA and Harvard, or two Chicago systems, is a common and easily avoided deduction.

How accurate is automated citing – and its limits

Automated generators are accurate for the mechanics – punctuation, italics, author order and field placement – because they apply a tested CSL template rather than remembered rules. That removes the most common formatting slips. But automation cannot judge the quality of the data you feed it.

• Bad metadata in, bad citation out. A database that mislabels a chapter as an article, or drops an author, carries that error straight into your reference.
• Style edge cases – a corporate author, a translated work, a social-media post, a legal case – are where any tool is most likely to need a manual check against the official manual.
• Capitalisation of titles often needs a human eye, since a tool cannot always tell a proper noun from an ordinary word.

Treat the generated entry as a strong first draft: verify the author, year, title and page numbers against the source itself, then trust the tool for the formatting.

Frequently asked questions

How many citation styles are there?

There is no fixed number – reference managers like Zotero ship with more than 10,000 CSL styles, most being journal-specific variants. In practice, around a dozen named styles (APA, MLA, Chicago, IEEE, Harvard and a few field-specific ones) cover nearly all student and academic writing.

What is the most common citation style?

APA is the most widely used overall, dominating psychology, education and the social sciences. MLA leads in the humanities, and Chicago is standard in history and publishing, so “most common” depends on your field.

What is the difference between APA and MLA?

APA uses an author-date in-text citation, sentence-case titles and a “References” list, suiting sciences where recency matters. MLA uses an author-page citation, title-case titles and a “Works Cited” list, suiting humanities where the exact location in a text matters more than the year.

Is Harvard the same as APA?

No, though they look similar. Both are author-date, but Harvard has no single governing manual, so its punctuation and ordering vary between universities. APA is a single, precisely defined standard published by the American Psychological Association.

Which citation style should I use for engineering?

Use IEEE for most engineering and computer-science work. It is a numbered style where a bracketed figure in the text, such as [1], points to a reference list ordered by first appearance rather than alphabetically.

Do I have to use the latest edition?

Follow whatever edition your instructor or journal specifies. When unspecified, use the current edition – APA 7th, MLA 9th, Chicago 18th – because databases and generators default to it and older rules can produce marked errors.

Related tools & guides

• Citation Checker
• How to Create a Hanging Indent
• What Is a Citation?