Citation – Definition – Introduction to Citation in Academic & Professional Writing

Explore the different ways to cite sources in academic and professional writing, including in-text (Parenthetical), numerical, and note citations.

What is a Citation?

A “citation” refers to the act of integrating ideas or words from another source into your speech or writing, along with adhering to the specific discourse conventions (or standardized ways of acknowledging sources) in a particular academic or professional field. “Citations” are required in academic and professional writing when writers summarize, paraphrase, or quote the words or ideas others. Writers may also cite known experts to enhance the authority of their arguments and observations.

In both academic and professional settings, the practice of citing sources—whether through quotations, paraphrasing, or summarizing—is a fundamental mark of professionalism. Being capable of citing sources correctly and critiquing the citations of others is a basic literacy in a knowledge economy.


Most generally, “citation” refers to the act of crediting a source of information. While “citation” is the formal term, there are several colloquial synonyms that people might use interchangeably, such as “attribution,” “reference,” or “mention.” In more casual or conversational settings, phrases like “backing up” one’s claim or providing “proof” might be used. When writers or speakers incorporate information from an external source, they might say they are “citing,” “attributing,” or “referencing” that source.

Related Concepts: Academic Dishonesty; Archive; Authority in Academic Writing; Canon; Copyright; Discourse; Hermeneutics; Information Has Value; Intellectual Property; Paraphrase; Plagiarism; Quotation; Scholarship as a Conversation; Summary


What Are The Three Major Ways of Citing Sources inside a Text?

While there are many different citation styles, as discussed below, there are only three major types of citations:

  1. In-text Citation (aka Parenthetical Citation)
  2. Numerical citation
  3. Note Citations

In-text Citation (aka Parenthetical Citation)

In-text Citation refers to the practice of placing bibliographical information in parentheses when sources/information are first introduced in a quote, paraphrase, or summary. The in-text citation is typically shorter and directs the reader to the full citation in the bibliography or reference list. In essence, all in-text citations are citations, but not all citations are in-text citations.

APA Example

When using APA style, writers place the author’s name, year, and page number (when available) in parentheses.

  • “As of 2022, about 12,700 nuclear warheads are still estimated to be in use, of which more than 9,400 are in military stockpiles for use by missiles, aircraft, ships and submarines” (Eagle, 2022).

And then at the end of their text, they list all of the sources they cited in the text, providing all of the bibliographical information users need to track down the source and read it:

  • Eagle, J. (2022, March 21). Animated chart: Nuclear warheads by country (1945-2022). Visual Capitalist.

Numerical Citation

Numerical Citation refers to when writers use numbers in brackets or superscript rather than parentheses to indicate to readers when they are quoting, paraphrasing, or summarizing:

IEEE Example
  • “As of 2022, about 12,700 nuclear warheads are still estimated to be in use, of which more than 9,400 are in military stockpiles for use by missiles, aircraft, ships and submarines”[1]

Subsequently, in the reference list at the end of their text, writers provided the bibliographic information following the order of the citations in the text:

Chicago (Turabian) Example
  • [1]J. Eagle, “Animated Chart: Nuclear Warheads by Country (1945-2022),” Visual Capitalist, Mar. 21, 2022. (accessed Jan. 03, 2023).

[ See Inclusive – Inclusive Language for a full-length example of Numerical Citations ]

Note Citation

Note Citations refers to when writers place citations numbers just as they do with numerical citations AND then provide all of the required bibliographical information in the text–as opposed to providing all that information at the end of the text in a list of references:

  • “As of 2022, about 12,700 nuclear warheads are still estimated to be in use, of which more than 9,400 are in military stockpiles for use by missiles, aircraft, ships and submarines” J. Eagle, “Animated Chart: Nuclear Warheads by Country (1945-2022),” Visual Capitalist, Mar. 21, 2022. (accessed Jan. 03, 2023).
Who says eucalyptus is a cure all Got any evidence to back up that claim Photo Credit Moxley

What Do All Citations Styles Have in Common?

Regardless of which citation style is used, attributions typically provide four types of bibliographical information:

  1. Name of Author(s)
  2. Title of source, whether it’s a book/article/website, etc
  3. Date of publication, if available
  4. Publisher information.

What Are the Most Popular Citation Styles?

Professional organizations (communities of practice) have unique ways of formatting citations. (See Wikipedia for a good listing of citation styles.)

Although style guides differ in regard to where the author’s name or publishing source is listed, they are all designed to ensure that proper credit is given to authors. As you know from your experience as a writer, developing insights and conducting original research is difficult and time consuming, so you can understand why people want to receive proper credit for their original ideas.

  • MLA Handbook, 9th Edition
    Modern Language Association style is primarily used in the fields of English and foreign languages.
  • Publication Manual of the APA: 7th Edition
    American Psychological Association’s style guide is used in psychology and education. Education and social science professors commonly ask students to follow the APA style for citing and documenting sources. APA differs from MLA in a number of ways, including the overall structure and format of the essay, but the major distinction between the two is APA’s use of the year of publication, rather than the page on which a particular quotation appears, for the in-text citation. APA requires in-text publication dates because of the particular importance of a study’s currency to research reports in the social sciences.
  • Chicago Style is used in many social science fields.
  • CSE (Council of Science Editors) is used by the scientific community
  • IEEE (Institute of Electrical and Electronic Engineers) is used by the engineering community.

What Critical Perspectives Do Readers Use to Assess Your Citations?

Citation in speech and writing serves as a barometer of ethos, especially trustworthiness. When audiences are engaged in critical literacy practices, they are likely to question a source’s

  1. Currency
  2. Relevance
  3. Authority
  4. Accuracy.

When audiences check the archive and find that authors are making inconsistent quotations, they are likely to question the character or ethos of the author.

In other words, subject matter experts tend to be well versed in the ongoing conversations that characterize the works of other subject matter experts. Experienced researchers tend to engage in strategic searching of the archive. They engage in critical literacy practices, asking questions, such as

  1. What is the status of knowledge on the topic?
  2. What is the ebb and flow of research on the topic–over time?
  3. What are the canonical texts?
  4. Who are the pioneers? How has their work changed the conversation?
  5. What knowledge claims are currently being debated?


Burke, K. (1941). The philosophy of literary form. University of California Press.
Oakeshott, M. (1962). Rationalism in politics. Basic Books.

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