Types of Plagiarism: 12 Forms Explained With Examples

Plagiarism comes in more forms than copy-and-paste. It can involve someone else's exact words, their ideas, their data or images, an inaccurate citation, or an entire piece of work produced by another person. Grouping the types by what's being misrepresented (language, ideas, sources or authorship) makes them easier to recognize and fix.

If you need a basic definition first, start with our overview of what plagiarism is. This article is the detailed field guide: twelve types, an invented example for each, and how to avoid it.

The types at a glance

Severity depends on your institution's policy, how much of the work is affected and whether it looks intentional. Treat the table as a map, not a ranking.

Language-level plagiarism

1. Verbatim plagiarism

Copying a source's words exactly, without quotation marks.

A student copies a sentence from a museum website, "The bridge took eleven years to build and cost the lives of over two dozen workers," into an essay with no quotation marks and no citation.

Fix: Put exact words in quotation marks and cite them, or paraphrase and cite. Copied text is also the type that similarity checkers catch most easily.

2. Mosaic plagiarism (patchwriting)

Weaving a source's phrases into your own sentences, often swapping a few synonyms, so the structure still belongs to the author.

Source: "The bridge took eleven years to build and cost the lives of over two dozen workers."
Student: "The bridge required eleven years of construction and claimed the lives of more than two dozen laborers."

Fix: Paraphrase from understanding with the source closed, then cite. Our guide to mosaic plagiarism walks through it.

3. Incomplete quotation

Quoting part of a passage correctly but letting the author's words continue past the closing quotation mark, or quoting without showing that words were removed.

"The bridge took eleven years to build" (Lee, 2020) and cost the lives of over two dozen workers.

The second half is still Lee's wording, but it sits outside the quote.

Fix: Make the quotation marks cover every copied word, and use ellipses or brackets where you shorten or adjust a quote.

Idea-level plagiarism

4. Paraphrasing without credit

Restating someone's idea in genuinely new words but not citing it. Many writers don't realize this counts, because nothing is copied.

A student writes that the bridge's high death toll led to the city's first workplace safety law, an argument they read in a historian's book, without mentioning the historian.

Fix: Cite ideas, interpretations and arguments, not just quotes. If you learned it from a source and it isn't common knowledge, credit it.

5. Translation plagiarism

Translating a text from another language and presenting it as your own writing.

A student finds a detailed Spanish-language article on the bridge, translates three paragraphs into English and submits them uncited.

Fix: Cite the original source. If you quote a passage you translated yourself, many citation styles ask you to say the translation is yours.

6. Data and visual plagiarism

Using someone else's data, charts, photos, diagrams or code without credit, or redrawing a chart and presenting it as your own.

A student recreates a graph of the bridge's construction costs from a university report in a spreadsheet and drops it into a slide deck with no source line.

Fix: Add a source note under every borrowed or adapted figure ("Adapted from [Author], [Year]"). Check whether images need permission to reuse, especially outside class.

Source-level plagiarism

7. Missing citation

Quoting or paraphrasing correctly in the text but forgetting the in-text citation or the reference entry.

An essay includes a properly paraphrased statistic about the bridge's daily traffic, but the paragraph has no citation and the source isn't in the reference list.

Fix: Cite as you write, not at the end. A citation generator can speed up formatting, but you still decide what needs citing.

8. Inaccurate or fabricated citation

Citing a source that doesn't say what you claim, citing the wrong page or author, or inventing a source entirely. Fabricated references are a known problem with AI chatbots, which can produce plausible but nonexistent citations.

A student cites "Harper, J. (2018). Bridges of the Industrial Age" for a casualty figure. The book doesn't exist; a chatbot suggested it.

Fix: Open every source you cite and confirm it supports your sentence. Never cite something you haven't seen.

9. Secondary-source plagiarism

Citing an original source you never read, when you actually found the information in a different source that cited it.

A textbook quotes an 1890s engineer's diary. The student cites the diary directly, as if they'd consulted it, and never mentions the textbook.

Fix: Cite the source you actually used. Most styles have a format for this, such as APA's "as cited in" for secondary sources.

Authorship-level plagiarism

10. Complete (global) plagiarism

Submitting an entire piece of work produced by someone else: a copied paper, a purchased essay, a friend's assignment or, under many current policies, text generated by an AI tool and presented as yours.

Fix: There's no partial fix. If you're overwhelmed, ask for an extension or help early. Our article on whether using ChatGPT is plagiarism covers the AI side in detail.

11. Collusion

Working with others on an assignment meant to be done individually, then submitting near-identical work. It differs from permitted collaboration, where the instructor allows group work.

Two lab partners share a single analysis and each submits it under their own name, though the assignment said reports must be written individually.

Fix: Clarify the collaboration rules. Discussing ideas is often fine; writing together usually isn't, unless it's a group project.

12. Self-plagiarism

Reusing your own earlier work as if it were new, without permission or disclosure. See our full guide to self-plagiarism.

Fix: Ask permission, cite your earlier work and add substantial new material.

Intentional vs. accidental

Every type above can happen on purpose or by accident. Messy notes, rushed deadlines and unclear rules cause many cases. Most policies still judge what's on the page, though intent can affect the consequences. Our guide to accidental plagiarism covers the habits that prevent it.

What checkers can and can't find

Similarity checkers compare your text against databases of web pages, publications and, in institutional tools, past submissions. They're strong on types 1–3 and sometimes catch close paraphrases. They're weak on idea plagiarism, translation, data reuse, collusion done in fresh words, fabricated citations and work written new by someone else.

Use a checker to catch quotes you forgot to mark and passages that stayed too close, then do the rest by careful reading.

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Key takeaways

• Plagiarism misrepresents one of four things: language, ideas, sources or authorship.
• Citing an idea doesn't excuse copied wording, and changing words doesn't excuse a missing citation.
• Translation, data, images and secondary sources all need credit.
• Checkers find copied text well and other types poorly, so good habits do most of the work.