Understanding plagiarism

Plagiarism means presenting someone else’s work as your own. In academic writing, plagiarizing involves using words, ideas, or information from a source without including a proper citation.

Plagiarism can have serious consequences for students and researchers, even when it’s done accidentally. To avoid plagiarism, it’s important to keep track of your sources and cite them correctly.

Why does plagiarism matter?

Plagiarism is a form of academic dishonesty. Whether you’re a student submitting a paper to a class or a researcher submitting to a journal, it’s expected that the work you submit is your own.

If you express an idea without mentioning the source, or paste a passage of text without properly quoting it, you’re taking credit for someone else’s work. This is true even if you didn’t deliberately set out to mislead your readers.

That doesn’t mean you can’t use other researchers’ ideas—building on others’ work is a key part of academic writing. But it’s important to clearly distinguish your own words and ideas from those of your sources.

If you’re caught plagiarizing, there can be serious consequences:

  • As a student, plagiarism can result in failing your course or even your degree.
  • As a professional academic, plagiarism can put your career and reputation at risk, and you could be held legally liable for copyright infringement.

The severity of the consequences depend on the type of plagiarism and the context—a first-year student who makes accidental citation errors is likely to be treated more leniently than a graduate student who deliberately steals someone’s work. But in all cases, an allegation of plagiarism is stressful and damaging to your academic success.

Types of plagiarism

Plagiarism takes various forms. It can involve reusing an entire document, rewriting a single paragraph, or pasting phrases or sentences without proper credit.

Common types of plagiarism
Copy-and-paste plagiarism Copy-and-paste plagiarism, also known as direct plagiarism, means copying a passage from a source without a citation.

If you want to use someone else’s exact words, you need to quote the source and cite it correctly.

Mosaic plagiarism Mosaic plagiarism means using various phrases, passages and ideas from different sources to create a kind of “mosaic” or “patchwork” of other researchers’ work, without proper citations.

Although the result is a completely new piece of text, the words and ideas aren’t new.

Self-plagiarism Self-plagiarism means reusing parts of your own previous work (e.g. submitting the same paper to a different class or recycling a dataset) without acknowledging this.

Self-plagiarizing is a problem because your readers expect the work to be new and original.

Global plagiarism Global plagiarism means submitting an entire work written by someone else. That includes having a friend write your paper for you or buying an essay from an online essay mill.

This is considered the most severe form of plagiarism, because you’re deliberately lying about the authorship of the work.

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Avoiding plagiarism

There are three simple rules you can follow to avoid plagiarism:

  1. When you want to include an exact phrase, sentence or passage from a source, use a quotation.
  2. When you want to express an idea or information from a source, paraphrase or summarize it entirely in your own words.
  3. Always cite the source when you quote, paraphrase, or summarize.

Citing sources

To cite correctly, choose a citation style and follow it consistently. Your university department or the journal you’re submitting to will usually specify which citation style to use, but the most common styles are APA, MLA and Chicago Style.

To cite a source, you need:

  1. A brief citation in the text, which may be a parenthetical citation or a numbered note.
  2. A full reference, which usually appears in a list at the end of your paper.

As well as citing scholarly sources like books and journal articles, keep in mind that you should also cite information or ideas that you found in non-academic sources, like websites, newspapers or YouTube videos.

Each type of source has its own reference format. Use our interactive tool to explore examples in MLA and APA.

Do I need to cite every piece of information?

Some information is considered common knowledge, which means it doesn’t need to be cited. Common knowledge is information that is widely known and easily verified.

For example, if you state that Washington DC is the capital city of the United States, or that the Amazon is the world’s largest tropical rainforest, no citation is required.

However, if you’re not sure whether something is common knowledge, it’s usually safest to cite the source.

How is plagiarism detected?

Your readers might notice plagiarism if the tone or style of the text changes between passages, or if they’re familiar with the source that’s been plagiarized.

Most universities also use plagiarism detection software such as Turnitin, which compares your text to a large database of other sources and highlights similarities.

If you’re worried about plagiarizing by accident, you can use a plagiarism checker yourself before submitting your paper to ensure you haven’t missed any citations.

However, keep in mind that some online plagiarism checkers are safer and more accurate than others. We’ve researched some of the free and paid options available to see how they compare.

Free plagiarism checker comparison Best plagiarism checker comparison

Free lecture slides

Are you a teacher or professor who would like to educate your students about plagiarism? You can download our free lecture slides, available for Google Slides and Microsoft PowerPoint.

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Frequently asked questions about plagiarism

What happens if you plagiarize?

The consequences of plagiarism vary depending on the type of plagiarism and the context in which it occurs. For example, submitting a whole paper by someone else will have the most severe consequences, while accidental citation errors are considered less serious.

If you’re a student, then you might fail the course, be suspended or expelled, or be obligated to attend a workshop on plagiarism. It depends on whether it’s your first offense or whether you’ve done it before.

As an academic or professional, plagiarizing seriously damages your reputation. You might also lose your research funding and/or your job, and you could even face legal consequences for copyright infringement.

Is paraphrasing considered plagiarism?

Paraphrasing without crediting the original author is a form of plagiarism, because you’re presenting someone else’s ideas as if they were your own.

However, paraphrasing is not plagiarism if you correctly cite the source. This means including an in-text citation and a full reference, formatted according to your required citation style.

As well as citing, make sure that any paraphrased text is completely rewritten in your own words.

Can you plagiarize your own work?

Although it sounds contradictory, you can indeed plagiarize your own work. This is called self-plagiarism. Self-plagiarism goes against the expectations of the reader that the paper you submitted is new and original.

You can plagiarize yourself by, for instance:

  • Submitting a document you previously submitted for a different course
  • Using ideas or data from a previous paper without correctly citing yourself as the source

Although self-plagiarism is often unintentional, it can have serious consequences. Be sure to cite your previous work or discuss the decision to use your old paper with your professor.

Are plagiarism checkers accurate?

The accuracy depends on the plagiarism checker you use. Scribbr is the most accurate plagiarism checker. Many free plagiarism checkers fail to detect all plagiarism or falsely flag text as plagiarism.

Take a look at this comparison of free and paid plagiarism checkers for students to find the most accurate plagiarism checker.

The accuracy is determined by two factors: the algorithm (which recognizes the plagiarism) and the size of the database (with which your document is compared).

Size of the database

Many free plagiarism checkers only check your paper against websites – not against books, journals or papers previously submitted by other students. Therefore, these plagiarism checkers are not very accurate, as they miss a lot of plagiarism.


Most plagiarism checkers are only able to detect “direct plagiarism”, or instances where the sentences are exactly the same as in the original source. However, a good plagiarism checker is also able to detect “patchwork plagiarism” (sentences where some words are changed or synonyms are used).

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