Overview

A citation is a formal reference to a published or publicly available source used to support, illustrate, or document information in a written work. Citations identify where specific material—such as a book, a journal article, a website (online source) or an image—originated, and they allow readers to locate and evaluate that source for themselves. Proper citation acknowledges the original author or creator (creator information) and distinguishes a writer’s contributions from material drawn from others.

Types and common formats

Citations take several forms depending on the discipline and purpose. Common approaches include brief in-text citations that correspond to a reference list, footnotes or endnotes that provide bibliographic detail or commentary, and numbered styles that use a numerical reference list. Major style families include:

  • Author–date styles (for example, APA) that use short parenthetical citations in the text and a reference list ordered alphabetically by author.
  • Note styles (for example, Chicago notes and bibliography) that use footnotes or endnotes for full details and may include a bibliography for broader reading.
  • Humanities styles (for example, MLA) that emphasize author and page references for literary and textual analysis.
  • Numeric and technical styles (for example, Vancouver or IEEE) common in medicine, engineering, and the natural sciences, using numbered citations linked to a reference list.

Elements of a citation

A clear citation normally contains enough information to identify and find the source: author or creator, title, publication venue or publisher, date, and location details such as page numbers, DOI, or other persistent identifier. For online works, include a stable link or identifier provided by the publisher; for archival materials or special collections, include repository and collection identifiers where possible. Many style guides specify the precise order and punctuation for these elements—consult a manual or institutional guide (how to cite).

When and how to cite

Cite sources when you quote directly, paraphrase another person’s ideas, use unique data or images created by someone else, or rely on specific facts that are not common knowledge. If a fact is widely known (for example, a broadly taught historical date), it may not require citation; when uncertain, cite. In practice, indicate sources through parenthetical citations, superscript numbers, or footnotes as required by the chosen style, and provide a corresponding full reference in a bibliography, reference list, or works cited section.

Digital identifiers and access

Persistent identifiers such as Digital Object Identifiers (DOIs), handles, or stable repository links improve the longevity and reliability of citations by pointing to a fixed record for an article, dataset, or other digital object. When a DOI or stable identifier is available, include it because it helps readers and indexing services locate the material even if the web location changes. For images and multimedia, include creator, title, and the hosting repository or database information.

Ethics, attribution, and plagiarism

Citations are central to academic and professional integrity. They give credit to original creators and help readers evaluate the basis for claims. Failing to cite appropriately can constitute plagiarism (plagiarism), which institutions often treat seriously and which can carry academic or professional penalties. Institutional policies and standards for attribution vary; consult local rules and academic policies (academic policies) when preparing work.

Tools, management, and best practices

Use reliable style guides and citation management tools to keep references organized and to insert citations consistently. Common reference managers can store metadata, format bibliographies in different styles, and integrate with word-processing software. Keep careful records while researching: note full bibliographic details, access dates for unstable resources, and any permissions required for reuse of images or data. When in doubt about whether to cite, err on the side of attribution.

Special media: images, datasets, and multimedia

For non-textual sources, provide the creator or rights holder, title or description, date, and repository or platform where the item is held. When using images, note any license or permission requirements and follow fair-use or licensing terms. For research that uses datasets, cite the dataset with a persistent identifier when available and provide information needed to reproduce analyses, such as version numbers, access conditions, and any transformations applied.

Common mistakes and practical advice

  • Avoid incomplete citations: missing author names, dates, or page numbers reduce usefulness.
  • Keep citation style consistent throughout a document; follow publisher or instructor instructions.
  • Verify automated citations generated by software against an official style manual.
  • Use institutional or subject-specific guides and online resources for examples (online guides, academic article examples).

For additional guidance on citation formats, style rules, and examples across media, consult reference manuals, library services, or editorial policies provided by publishers and educational institutions. Reliable guidance and careful record-keeping make citations a practical tool for transparency, credit, and the scholarly conversation.

Further reading and resources: general writing guides and institutional pages often summarize style choices and provide templates (how to cite, books on style, creator information resources).

See also: guidance on citing images, information on plagiarism, and academic policies for conduct and attribution.