The main types of plagiarism are direct, global, mosaic, paraphrasing, self, source-based, accidental, and AI-generated plagiarism. They differ in how much borrowed material is involved and whether the writer meant to deceive, but every one of them presents someone else’s words, ideas, or work (or your own earlier work) as new and original without giving proper credit.
This guide defines each type in plain language and gives a short example, so you can spot the problem in your own drafts before a plagiarism checker or an instructor does. It belongs to our academic integrity series, and it builds on the basics in what is plagiarism.
Types of Plagiarism at a Glance
The table below puts all eight common types side by side. Each one gets its own section further down.
| Type | What it means | Typical example |
|---|---|---|
| Direct (verbatim) plagiarism | Copying a passage word for word, without quote marks and without a citation | Pasting two lines from an article into your essay |
| Global (complete) plagiarism | Handing in an entire work that someone else produced | Turning in a paper bought from an essay mill |
| Mosaic (patchwork) plagiarism | Stitching phrases from several sources into one text | Swapping a few terms in lines taken from three articles |
| Paraphrasing plagiarism | Rewording a source too lightly, or without citing it | Changing a few terms but keeping the original structure |
| Self plagiarism | Reusing your own earlier work without permission or disclosure | Giving one essay to two courses |
| Source-based plagiarism | Misrepresenting the sources you used | Citing a book you never opened |
| Accidental plagiarism | Borrowing without credit through carelessness or poor notes | Forgetting a citation after mixing up your notes |
| AI-generated plagiarism | Presenting machine-written text as your own work | Handing in a chatbot answer without saying so |
Direct Plagiarism (Verbatim Plagiarism)
Direct plagiarism, also called verbatim plagiarism, means copying a passage word for word from a source and presenting it as your own writing. The copied text appears without quotation marks and without a citation. The reader cannot tell it came from someone else. Most people picture this type first. Software also finds it easily, because the text matches the original exactly.
Quoting is not the problem. Putting the author’s exact text inside quotation marks, with a citation, is fine. The Harvard Guide to Using Sources describes verbatim plagiarism as copying a passage with no quotation marks or credit, even when it is only one sentence.
Example: A source says, “Urban gardens reduce street-level temperatures by shading pavement and cooling the air.” A student writes the same line in their essay without quote marks or a citation.
Global Plagiarism (Complete Plagiarism)
Global plagiarism, sometimes called complete plagiarism, means handing in a whole piece of work that another person created. Nothing in the paper is original to the student. The student is taking credit for someone else’s work. The work might come from a classmate, a paper mill, a freelancer, or an older student’s essay found online.
Most schools treat this as the most serious kind. It involves a deliberate choice to deceive, and it replaces the student’s own research and thinking. Penalties often include a failing grade for the course and a formal academic integrity case.
Example: A student pays a website for a finished 1,500-word essay on climate policy, changes the name on the title page, and turns it in as their own assignment, submitting another person’s work without credit.
Mosaic Plagiarism (Patchwork Plagiarism)
Mosaic plagiarism, also known as patchwork plagiarism or patchwriting, happens when a writer blends phrases or ideas from several sources into one paragraph. The borrowed sentence fragments appear without quotation marks or citations. A few terms are often swapped for synonyms, so the text looks original at a glance. The structure and key phrases still belong to the sources.
This is one of the most common types of plagiarism in research papers. The draft gets built piece by piece from open tabs. The University of North Texas library explains the problem in its guide to mosaic plagiarism and patchwriting.
Example: A paragraph opens with a clause from one article, continues with a phrase from a second, and closes with a line from a third. Each piece has a term or two changed, and none is credited.
Paraphrasing Plagiarism
Paraphrasing plagiarism means restating another writer’s ideas in your own wording, but doing it badly or without a citation. A paraphrase should change both the wording and the structure of the original. It also needs a citation, because the idea is still not yours. Yale’s Poorvu Center offers a useful breakdown of a fair paraphrase and what separates it from a copy with a few swapped terms.
Inadequate Paraphrase
An inadequate paraphrase keeps the original sentence structure and replaces only some words. The result reads like the source with a light disguise, and a checker or an instructor will still see the match.
Uncited Paraphrase
An uncited paraphrase uses genuinely new wording, but it never names the author who came up with the idea. The writing is yours, and the thinking is not. Another person’s finding or argument always needs to be properly credited.
| Version | Original | Weak paraphrase |
|---|---|---|
| Inadequate paraphrase | “Sleep loss impairs memory formation in teenagers.” | Lack of sleep damages memory formation in teens. |
| Uncited paraphrase | A researcher’s finding that late school start times raise grades | Later start times lead to better grades, with no author or source named. |
Self Plagiarism
Self plagiarism means reusing your own earlier work, in whole or in part, without permission or disclosure. You cannot steal from yourself in a legal sense. Academic rules still treat it as a breach, because the reader believes the work is new. It covers submitting the same paper to two courses, recycling paragraphs from an old assignment, and publishing overlapping articles without saying so.
If you want to build on a previous paper, ask your instructor first and cite your earlier work. We cover the rules, exceptions, and penalties in our full guide to self plagiarism.
Example: A student hands in last term’s history essay, with a new title, to a different course this term and tells nobody.
Source-Based Plagiarism
Source-based plagiarism means misrepresenting the sources behind your work. The writer does not copy text. Instead, the writer gives a false picture of where the information came from. Typical cases include citing a source you never read, or inventing a reference. Others include quoting a secondary source as if you had consulted the original, or citing a real source for a claim it does not make.
It matters because a citation is a promise. The reader trusts that the cited source backs up the claim. A false or padded bibliography damages that trust. This is true even when every line is in the student’s own words, since another researcher cannot trace the evidence.
Example: A student finds a quote inside a review article, then cites the original book as if they had read it. They never opened the book, and the quote was taken out of context.
Accidental Plagiarism
Accidental plagiarism happens when a writer borrows someone else’s work without credit, through carelessness, not intent. Because the writer did not mean to deceive, it feels different from the deliberate types. Many schools still treat it as plagiarism. Instructors and plagiarism checkers read the text, not the writer’s mind, so every borrowed sentence needs credit.
Common Causes
- Messy or incomplete notes
- Forgotten quote marks
- Unclear citation rules
- Paraphrasing too closely out of habit
- Losing track of the original source
The good news is that accidental plagiarism is the easiest kind to prevent, since better habits fix it. Mark every quote in your notes, record the source the moment you copy anything, and run a final citation check before you submit.
Example: A student copies a line into their notes with no quote marks. Weeks later, they forget it was not their own wording and paste it into the draft with no citation.
AI-Generated Plagiarism
AI-generated plagiarism means presenting text produced by a chatbot or other generative tool as your own writing, or using it in a way your course rules do not allow. Policies vary by school and by instructor. Some courses ban generative AI altogether, and others allow it for brainstorming if you disclose it. AI tools can also reproduce phrases from their training data and invent sources. Both can lead to verbatim or source-based plagiarism without any warning.
Check the syllabus before you use any tool, and keep a record of how you used it. Submitting AI-written text without disclosure is the quickest way to break the rules. Cornell’s Center for Teaching Innovation explains how AI and academic integrity interact in coursework.
Example: A student pastes an assignment prompt into a chatbot and hands in the answer unchanged, even though the syllabus says all writing must be the student’s own.
How to Avoid Each Type of Plagiarism
Most of these problems come down to credit. Giving the original author clear credit, in the right form, prevents nearly all of them. Students who follow a few steady habits rarely run into trouble. This table matches each type with the habit that stops it.
| Type | How to avoid it |
|---|---|
| Direct plagiarism | Put exact text in quotation marks and add a citation |
| Global plagiarism | Write your own paper, and ask a tutor or writing center for help instead of buying one |
| Mosaic plagiarism | Close your sources before writing, then draft from your own understanding |
| Paraphrasing plagiarism | Change the structure as well as the wording, and cite the idea |
| Self plagiarism | Get permission and cite your earlier work |
| Source-based plagiarism | Cite only what you have read, and check that each source supports the claim |
| Accidental plagiarism | Keep careful notes and record every source when you find it |
| AI-generated plagiarism | Follow your course policy and disclose any AI help |
Frequently Asked Questions About Types of Plagiarism
What are the most common types of plagiarism?
The most common types are direct plagiarism, mosaic plagiarism, paraphrasing plagiarism, self plagiarism, and accidental plagiarism. Global, source-based, and AI-generated plagiarism are also widely recognized, and many university policies now cover them, so students should check their own school’s rules.
What is the difference between direct and global plagiarism?
Direct plagiarism copies specific passages word for word. Global plagiarism takes an entire work and submits it as your own. It can be a few lines inside an otherwise original paper, but global plagiarism leaves nothing original in the submission.
Is accidental plagiarism still plagiarism?
Yes, in most academic settings. The writer may not have meant to deceive, but the work still uses someone else’s words or ideas without credit. Intent can affect the penalty, though it rarely removes the problem.
Can paraphrasing be plagiarism?
Yes. A paraphrase is plagiarism when it stays too close to the original wording or structure, or when it is used without a citation. A good paraphrase uses your own wording and structure and still credits the source of the idea.
Is using AI to write an essay plagiarism?
It can be. If you submit AI-written text as your own work, or you use AI against your course rules, most schools treat it as an academic integrity violation. Read your syllabus, and disclose any permitted use.
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Terry is a Chicago-based writer and editor who creates practical, student-friendly guides on essay writing, research, and citation styles (APA, MLA, and Chicago). He’s spent 15+ years editing educational content and building clear examples that help readers apply rules without guessing. When he’s not revising drafts, he’s usually turning messy notes into clean outlines and hunting down the one detail everyone skips.