Overview
Plagiarism means presenting someone else’s words, ideas or work as your own without proper credit. The different types describe how that happens: copying text word for word, borrowing structure or ideas, misusing citations, recycling your own work, or passing off AI-generated text. Names vary between universities, and several overlap, so it helps to think of them in four groups.
The examples below all borrow from one invented source sentence: “Urban trees lower summer street temperatures, reduce stormwater runoff and measurably improve residents’ sense of wellbeing.” (Author, 2022)
For a shorter introduction to plagiarism itself, start with what is plagiarism?
Copying words
1. Direct plagiarism
Copying text from a source word for word without quotation marks or a citation. Also called verbatim or clone plagiarism. It is the most clear-cut type and the easiest for a checker to find.
Example: “Urban trees lower summer street temperatures, reduce stormwater runoff and measurably improve residents’ sense of wellbeing,” written as your own sentence with no quotation marks or citation.
2. Global (complete) plagiarism
Submitting an entire piece of work that someone else wrote as your own: a paper found online, a classmate’s essay, or one bought from a writing service. It is treated as the most serious form almost everywhere.
Example: downloading a full essay on urban forestry and handing it in under your name.
3. Self-plagiarism
Reusing work you already submitted or published, and presenting it as new, without permission or a citation. Our full guide covers self-plagiarism in detail.
Example: copying three paragraphs about urban trees from last year’s geography essay into this year’s environmental science paper without telling either instructor.
Borrowing without credit
4. Paraphrasing plagiarism
Rewording a source but keeping its sentence structure, or presenting a paraphrase without a citation. A paraphrase still uses someone else’s idea, so it still needs credit.
Example: “Trees in cities reduce street heat in summer, cut rainwater runoff and noticeably boost how well people feel.” Same structure, swapped words, no citation.
5. Mosaic plagiarism
Weaving phrases from a source into your own sentences without quotation marks, so the paragraph reads as original but is stitched together from borrowed language. It often draws from several sources at once.
Example: “Planting programmes matter because urban trees lower summer street temperatures while also helping to reduce stormwater runoff in dense neighbourhoods.”
6. Patchwork plagiarism (patchwriting)
Often used as another name for mosaic plagiarism. Some writing instructors use “patchwriting” for the milder version that happens while students are still learning to paraphrase: staying too close to the source’s wording, sometimes with a citation but without quotation marks.
Example: “Urban trees reduce summer street heat, lower stormwater runoff and measurably improve how residents feel (Author, 2022).” Cited, but still too close to be a real paraphrase.
7. Incremental plagiarism
Borrowing small pieces, such as a striking phrase, a sentence or a key term, without credit, inside work that is mostly your own. Each piece is small, but together they misrepresent whose thinking the reader is seeing.
Example: an otherwise original essay that includes the phrase “measurably improve residents’ sense of wellbeing” without quotation marks.
8. Accidental plagiarism
Any of the above, done by mistake: a lost citation, a quotation pasted into notes without its source, or a phrase you remembered without realising it was not yours. Intent affects consequences, but most policies still treat it as plagiarism.
Example: your notes say “trees reduce runoff and improve wellbeing” with no source, and the claim ends up in your essay uncited.
Misusing sources
9. Source-based plagiarism
Problems with the citations themselves: citing a source you did not read, citing the wrong source, citing a secondary source as if you read the original, or inventing a source. It can also mean using data or findings without credit.
Example: quoting the original 2022 study when you only read a news article that quoted it, and citing the study as if you had read it yourself.
AI-assisted plagiarism
10. AI-assisted plagiarism
Submitting text produced by an AI tool such as ChatGPT as your own work, where your course does not allow it or you did not disclose it. Using AI to paraphrase a source so it slips past a plagiarism checker also falls here: the idea is still borrowed, and the rewording is not yours either.
Example: asking a chatbot to “write a paragraph on the benefits of urban trees” and pasting its answer into your essay without disclosure.
Whether AI use counts as plagiarism depends heavily on the rules you are working under. Our guide Is using AI plagiarism? covers the nuance, and how to cite ChatGPT shows how to credit it when it is allowed.
Which types are most serious?
Institutions weigh plagiarism by how much was taken, whether it was deliberate and whether it was a first instance. As a rough guide, from generally more to less serious:
| Type | Why it is weighed this way |
|---|---|
| Global plagiarism, undisclosed AI-written work | The whole submission is not the student’s own work |
| Direct plagiarism, source-based fabrication | Clear copying or invented evidence |
| Mosaic, paraphrasing, self-plagiarism | Often partly deliberate, depends on extent |
| Patchwriting, incremental, accidental | Often a skills issue, usually handled as a learning opportunity at first |
This is a general pattern, not a rule. Your institution’s academic integrity policy sets the actual categories and consequences.
Related misconduct that is not plagiarism
Some integrity breaches sit next to plagiarism rather than inside it. Collusion is working with another student on work that should be individual, then submitting it as your own. Contract cheating is paying someone, or a service, to produce the work. Fabrication is inventing data or results. Policies often list these separately, but the underlying problem is the same: the work does not honestly show what you did.
How to avoid every type of plagiarism
- Record sources as you research. Put the citation next to every note, and mark copied text with quotation marks immediately.
- Paraphrase from memory. Read the source, close it, write the idea in your own words, then check back and add the citation.
- Cite ideas, not just quotations. If the idea came from a source, credit it.
- Ask before reusing your own work or using AI, and disclose what you did.
- Check the draft. A plagiarism checker highlights copied and closely paraphrased passages and shows the matching source, so you can quote, cite or rewrite before you submit.
Our guide to avoiding plagiarism goes deeper on each habit. To format the citations themselves, the citation generator in the web app handles APA, MLA, Chicago, Harvard and more, free with an account.