Citation & Citation Types: When & Why You Must Cite Sources in Academic & Professional Writing

Citation is crucial to establishing authority in speech and writing--especially when the target audience is well educated and likely to engage in critical literacy practices. Learn when to cite, how to cite, and which citation style to use so your texts and arguments will be clear and persuasive--and avoid plagiarism and academic dishonesty.      

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What is a Citation?

A “citation” refers to the formal way of giving credit to the sources of information or ideas used in a work. As explained below, citations can manifest as in-text acknowledgments (aka parenthetical citations), numbered references, or notes. The exact format varies with the style guide employed, such as APA, MLA, or Chicago. These citations often correspond to a comprehensive list at the document’s end, like a bibliography or reference list.


The term “citation” has several synonymous terms that writers and speakers may employ, including “attribution,” “reference,” “support,” “backing,” or “proof.” When writers or speakers use information from another source, they may state that they are “citing,” “attributing,” or “referencing” that particular 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

Why Do Citations Matter?

Knowing how to cite sources (e.g., quotations, paraphrases, and summaries) is a basic literacy in a knowledge economy.

In life, ideas matter. Texts matter. They are a form of intellectual propertyand intellectual capital. For example, consider the Harry Potter media franchise, which is estimated to be worth $25 billion in 2016 (Meyer 2018). Educated readers understand information has value. It’s a commodity that is protected by intellectual property and copyright laws.

Authority – Citation as a Rhetorical Appeal

Beyond satisfying mores associated with intellectual property, citations may be used for rhetorical purposes. For instance, writers may attribute sources when

  1. they aim to contextualize information, to convey a summary of a text or scholarly conversation so readers can better understand what’s known and unknown about the topic
  2. they believe their use of citations will give their ideas more authority.

Within any field, there are seminal thinkers and investigators whose work has dramatically shifted the narrative or deepened our understanding of a topic. These individuals have, in essence, changed the conversation. When a writer meticulously and judiciously cites these recognized experts, it serves as a beacon of credibility and assures the reader of the depth and rigor of the research.

In contrast, a seemingly arbitrary selection of sources, particularly if they don’t include these key voices, can dilute the perceived authority of a piece. Thus, by aligning their work with established voices in the field, writers bolster their own standing and foster trust with their audience.


For readers, citations are a signal of professionalism and rigor — when employed correctly. When absent or used incorrectly, the converse is true. Thus, when writing you can assume that your citation practices will signal how intellectually open and how educated you are.

Score Keeping – Social Capital

In academic and scientific research, another function of citations is as a kind of ‘score keeping.’ Scholars and researchers aim to contribute insights that will leave a lasting imprint on discussions within their domain. When their works resonate powerfully, they become entrenched in the ever-growing reservoir of human knowledge. Over time, consistently cited works can achieve a “canonical” status, signaling their enduring importance.

For academics and investigators in for-profit research labs, being the author of influential works or being frequently cited is not just an intellectual achievement: it serves as a form of social capital.

Scholars who find their works frequently cited see an expansion in their professional networks, leading to potentially greater opportunities. In many contexts, such as in the U.S., this recognition can translate into tangible benefits. Scholars who are recognized for their impactful contributions often find doors opening to grants, speaking engagements, and even financial opportunities like book royalties. Thus, citations not only validate research quality but can also elevate a scholar’s influence and value within their discipline.

Note, e.g., the screenshot below from Charles Darwin’s Google Scholar page: As of 1/23/22, 60,382 writers had published articls citing Darwin, making him a Michael-Jordan level scholar. And unlike Jordan’s all-time record, Darwin’s continues to score points as others cite his work!

Charles Darwins' Google Scholar Profile

For researchers, citations are a way of keeping track of the Conversation of Humankind–a concept articulated by Oakeshott in 1962 to account for how people develop knowledge by engaging in ongoing debate, dialog, and reflection:

“[W]e are the inheritors, neither of an inquiry about ourselves and the world, nor of an accumulating body of information, but of a conversation, begun in the primeval forests and extended and made more articulate in the course of centuries. It is a conversation which goes on both in public and within each of ourselves. . . . Education, properly speaking, is an initiation into the skill and partnership of this conversation in which we learn to recognize the voices, to distinguish the proper occasions of utterance, and in which we acquire the intellectual and moral habits appropriate to conversation. And it is this conversation which, in the end, gives place and character to every human activity” (Oakeshott 1962).

Thus, in Writing Studies, this process of making meaning through dialog and conversation enables writers to “stand on the shoulders of giants!”

“If I have seen further, it is by standing on the shoulders of giants.” 

Sir Isaac Newton

When are Citations Required?

In academic and professional writing, proper crediting of sources isn’t just good practice—it’s a testament to professionalism, credibility, and authority. Here’s when you should definitely cite:

  1. Direct Use of Content: When you directly quote, paraphrase or summarize another’s ideas, words, or creative media. If you cite three or more words from the original or even one word that was coined by the author, you should acknowledge your indebtedness by placing quotation marks around the borrowed term(s).
  2. Influence of Original Works: If the primary concepts or perspectives of an article, paper, or presentation are heavily influenced by someone else’s original work, even if not directly quoted.
  3. Authority and Reliability: Proper citations are essential for readers to assess your authority as writer and the accuracy and reliability of your source(s).

Ethical Implications

Not citing under the above circumstances can lead to

  • Accusations of plagiarism or academic dishonesty in educational and workplace contexts.
  • Legal consequences in public and professional contexts, especially when one presents another’s work as their own.
Infographic Credit <a href=httpswwwflickrcomphotos161099408N0341518026592 target= blank rel=noreferrer noopener>How to Defend Against Online Plagiarism<a> by <a href=httpswwwflickrcomphotos161099408N03 target= blank rel=noreferrer noopener>harrisxiong<a> is licensed under <a href=httpscreativecommonsorglicensesby20ref=openverse target= blank rel=noreferrer noopener>CC BY 20<a>

Types of Citations

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).

Citation Needed Who says eucalyptus is a cure all Got any <a href=httpswordpress 791598 2945919cloudwaysappscomsectionresearch>research<a> to back that claim Photo Credit Moxley

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 is Bibliographical Information?

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 Critical Perspectives Do Readers Use to Assess Your Citations?

Citation may also serve 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?

Works Cited

Oakeshott, M. (1962). Rationalism in politics. Basic Books.
Meyer, K. (2018). Harry Potter’s $25 billion magic spell. Money.