What Is Plagiarism? 8 Types With Examples

Plagiarism is presenting another person's words, ideas, data or work as your own without giving credit. It can be deliberate or accidental, and it covers copied text, stitched-together paraphrase, reused coursework, uncredited AI output and unacknowledged translation. This guide defines it, shows eight types with examples, and explains how to avoid each.

What is plagiarism?

Plagiarism is using someone else's words, ideas, data, images or structure and presenting them as your own, without clear credit. The definition has three parts: something belongs to another person (or to your earlier self), you used it, and the reader was not told. Remove any one of the three and it is no longer plagiarism. Quoting a sentence with quotation marks and a citation is scholarship, not theft.

Intent matters for how an institution responds, but not for whether the text is plagiarized. An essay that copies a paragraph by mistake still contains copied material. Most universities, schools and employers treat deliberate and careless copying differently when they decide on a penalty, yet both are expected to be corrected.

Three quick tests before you submit

Ask these before you submit anything:

1. Could a reader tell which words and ideas are mine and which came from elsewhere? If not, add attribution.
2. Did I put every borrowed phrase in quotation marks, or change it beyond swapping a few words and still cite it?
3. Is every source I used in my reference list, and every item in my reference list used in the text?

If the answer to any is no, fix it before you submit.

The eight types of plagiarism

Different institutions use different labels, and some merge these categories. What follows is a practical grouping, not an official standard.

1. Direct plagiarism

Copying a passage word for word and presenting it as yours.

Original (a published article): "Urban trees lower summer street temperatures by providing shade and releasing water vapor."

Plagiarized: Urban trees lower summer street temperatures by providing shade and releasing water vapor.

Fixed: As one source puts it, "urban trees lower summer street temperatures by providing shade and releasing water vapor" (Author, 2020, p. 14).

How to avoid it: copy exact wording only into quotation marks, with the page number, and do it in your notes at the moment you copy it.

2. Mosaic plagiarism or patchwriting

You take phrases from two or three sources, swap a few words for synonyms, and join them. The sentence structure is still theirs.

Original: "Remote workers often report greater autonomy but weaker ties to colleagues."

Patchwritten: Home-based staff frequently report more autonomy but weaker ties to co-workers.

Better: People who work from home tend to feel freer to organize their day, yet they can feel less connected to their team (Author, 2021).

The patchwritten version keeps the original's order of ideas and nearly its whole skeleton. Real paraphrase starts from understanding: close the source, explain the point from memory, then check you did not follow its structure. Our guide to paraphrasing vs plagiarism shows graded examples.

3. Self-plagiarism

Handing in an essay (or large parts of one) that you already submitted for another course, or republishing your own article as new, without telling the reader. Your own earlier work is still something you must credit, because the reader assumes new work for this assignment.

How to avoid it: ask your instructor or editor before reusing anything. If reuse is allowed, cite your earlier paper like any other source. In publishing, journals and publishers set their own rules on prior publication, so read them first.

4. Accidental plagiarism

No intent to deceive, just poor habits: copied sentences pasted into a draft with no mark, a missing quotation mark, a source forgotten in the reference list, or a half-remembered idea written as your own.

How to avoid it: use a note-taking system that separates three things, for example a tag for direct quote, my paraphrase and my own idea. Add the citation the moment you note something down, not at the end. Our guide on how to avoid plagiarism walks through that routine.

5. Source-based plagiarism

Here the text is yours but the sourcing is dishonest or careless:

• citing a source you never read (copying a citation from another paper's reference list);
• inventing or misattributing a quotation;
• citing a secondary source as if you had consulted the original;
• listing a reference that does not support your claim.

If you only read a study through a textbook's summary, say so, for example "Smith, 1998, as cited in Jones, 2015" in APA style. The difference between primary and secondary sources matters here.

6. AI-assisted plagiarism

Submitting text produced by an AI writing tool as your own work when your institution or employer does not allow it, or allows it only with disclosure. Rules vary widely: some courses ban generative AI entirely, some allow it for brainstorming, some require a statement of how you used it. Read the policy in your syllabus or workplace guidelines, and when in doubt, ask. Whether such use counts as plagiarism is covered in more depth in our guide to whether using AI is plagiarism.

AI output can also reproduce wording from its training data, and can invent sources that look real, so anything you keep needs checking and citing.

7. Translation plagiarism

Translating a paragraph from another language and handing it in as your own. A translation is a new wording of someone else's ideas, so the original author is still owed credit. It is also common in research writing: a student finds a good article in a language their reader does not know and translates it without citing it.

How to avoid it: cite the original-language source. If you translated a quotation yourself, say so ("my translation"), and use quotation marks as you would for any quote.

8. Collusion

Working with others on something that had to be individual, so that two or more submissions share the same structure, wording or answers. Collaboration is normal in many courses, so the line is set by the assignment brief. If you are unsure whether group work is allowed, ask first and acknowledge helpers in a note if the rules permit.

What counts as plagiarism, and what does not

"Common knowledge" depends on your audience. If a fact would surprise or be unknown to your readers, cite it.

Consequences

The consequences depend on the institution and the context, so this section stays general and no figures are given.

• At school and university: penalties are set by each institution's academic integrity policy and can range from a required rewrite or a reduced grade to a failed course, and in serious or repeated cases formal disciplinary action. Read your own handbook.
• In publishing and research: journals and publishers may reject a manuscript or retract a published paper.
• At work: copied content can breach employment terms, client contracts or copyright.
• Legally: plagiarism is an ethical and academic concept, not a single legal offence. Copying can, however, also infringe copyright, and that is a legal matter that depends on the jurisdiction. This is general information, not legal advice.

What a similarity score does and does not prove

Tools that compare your text with other documents give you a similarity score: the share of your text that matches something in the sources they searched. That number is useful as a prompt to look again. It is not a verdict.

• A high score can come from properly quoted passages, a bibliography, standard phrases or a long quotation in a legal or scientific text.
• A low score does not prove originality. The tool only searched the sources it has, and a paraphrased idea or a translated passage can pass unnoticed.
• A tool cannot tell why a match exists. Only a person reading the passages and the sources can judge.

The AdeptWrite Plagiarism Checker searches open encyclopedic and academic sources, lists every source it searched, and highlights the matching passages. It needs at least 30 words and accepts up to 6,000 characters per run. A result of 0% means no overlap was found in the sources searched, not that the text is guaranteed original, and the checker is not a replacement for your institution's own system. The AI Content Detector is a separate tool that gives an estimate of whether a text looks machine-written. It is an estimate, not proof, and it should never be the only evidence against anyone.

A pre-submission checklist

• ☐ Every direct quotation is in quotation marks with a page or paragraph reference.
• ☐ Every paraphrase has a citation and does not follow the source's sentence structure.
• ☐ Every statistic, date and claim from a source is cited.
• ☐ I did not reuse earlier work without permission.
• ☐ I followed the AI policy for this assignment and disclosed any AI use that was required.
• ☐ Translated material is credited to the original source.
• ☐ My reference list and in-text citations match each other.
• ☐ I ran a similarity check, read each flagged passage and fixed real problems.

Common mistakes

• Thinking a citation alone fixes a copied sentence. If the words are copied, they need quotation marks as well.
• Changing a few words and calling it a paraphrase. Structure and order of ideas count.
• Trusting "0%" as a guarantee. It describes only the sources searched.
• Ignoring the reference list. Cite everything you took from a source, and list only what you used.
• Leaving it to the end. Most accidental cases start with notes that did not record where an idea came from.

Using AdeptWrite to stay on the right side

Start with the Paraphrasing Tool only as a drafting aid: it rewrites sentences in seven modes, but a rewritten sentence from someone else's idea still needs a citation. Build your citations with the Citation Generator (APA 7, MLA 9, Chicago, Harvard, IEEE) and check the output against your style guide. Before submitting, run the Plagiarism Checker, read what it flags, and fix those passages yourself.

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