What is plagiarism?

Plagiarism is a common problem, primarily among students. Merriam-Webster Dictionary defines plagiarism as follows:

“To steal and pass off (the ideas or words of another) as one’s own: to use (another’s production) without crediting the source

The two highlighted snippets require further explanation:

  1. Many people think plagiarism is stealing someone else’s words, but it also means stealing someone else’s ideas. In other words, even if you paraphrase a text, the idea still needs to be cited.
  2. The phrase “without crediting the source” means that it’s okay to use the words and ideas of others, but you have to cite the source to avoid committing plagiarism.

Types of plagiarism

Plagiarism takes various forms. It ranges from reusing an entire document to rewriting a single paragraph. In the end, all types of plagiarism come down to passing off someone else’s ideas or words as your own.

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

If you really want to include a passage from another source word for word, you should learn how to quote it.

Mosaic plagiarism Copying and pasting different pieces of text together to create a kind of “mosaic” or “patchwork” of other researchers’ ideas is plagiarism.

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

Self-plagiarism When you use parts of your previous work (e.g. a paper, a literature review or a dataset) without properly citing it, you commit what’s called self-plagiarism.

Although it sounds a bit crazy to be penalized for plagiarizing your own work, you should know that it is done because it goes against the expectations of the readers of your paper. They expect the work to be original.

Global plagiarism When you use someone else’s paper, you are committing plagiarism because you are pretending that the words and ideas are yours.

Using someone else’s work includes, for example, having a friend or family write the text for you or buying an essay from a so-called essay mill.

Consequences of plagiarism

The consequences of plagiarism depend on the type of plagiarism and whether you’re a first-year student, an experienced academic or a working professional.

These are some possible consequences of plagiarism:

  • Failing the course
  • Expulsion or suspension from your university
  • Copyright infringement
  • Ruined reputation and potentially the end of your career

Statements about plagiarism from universities and journals

The consequences of committing plagiarism vary according to the university or journal. Below, you can find statements from American University and the American Marketing Association (AMA). Always check the editorial policies and academic integrity code of your institution.

American University
“Sanctions for code violations [plagiarism] include loss of credit for the assignment, a failing grade for the course, a permanent notation on the transcript and dismissal from the university.”
American Marketing Association
“The penalty will be dictated by the nature of the offense and will likely include a ban on submitting to any journal published by the AMA for a period of time. All sitting Editors of AMA journals will be informed. … In extreme circumstances, the committee reserves the right to inform an author’s institution, depending on the seriousness of the offense.”

How to avoid plagiarism

To avoid plagiarism, simply follow these two steps:

  1. Quote, paraphrase or summarize the words or ideas from someone else.
  2. Give credit to the original source by including a citation in the text and the reference list.

What information needs to be cited?

Not all the information you use needs to be cited. Some information is considered common knowledge. Common knowledge is information that most people know. Here are a few examples:

  • Donald Trump is the president of the United States.
  • The Amazon is the world’s largest tropical rainforest.

The concept seems simple, but common knowledge can differ from person to person. Therefore, you should ask yourself who your readers are and what they consider to be common knowledge.

To help you, we developed a common knowledge test that tells you whether or not you need to cite the information.

Common knowledge test

How to cite sources

To cite your sources, you can use several citation styles, such as APA Style, MLA format or Chicago Style citations. Universities and journals often tell you which citation style to use. You should cite sources both in the running text with an in-text citation, footnote or endnote and in the reference list.

The in-text citation often only names the author(s) and the year of publication. The reference list contains all the information about a source, including the title of the work and the website URL.

Citation example (APA Style)

In-text citation
Recent research shows many of these Southern cities are dealing with crises which are compounded by rapid population growth (Watson, 2009).
Reference list entry
Watson, V. (2009). ‘The planned city sweeps the poor away…’: Urban planning and 21st century urbanisation. Progress in Planning, 72(3), 151–193. https://doi.org/10.1016/j.progress.2009.06.002

Every source type, such as a website, book or journal article, has different citation guidelines. For instance, you only include a URL when you cite a website. Be sure to check the guidelines of the citation style you use.

The easiest way to cite your sources is by using the Scribbr Citation Generator, as you only have to enter the website URL, book ISBN or journal DOI. All the relevant information is automatically retrieved and translated into a citation.

How to detect plagiarism

Detecting plagiarism isn’t too difficult. Either the reader of your text notices a change in tone and writing style when reading a passage or uses plagiarism detection tools.

These days, all documents submitted to a university or journal are automatically checked for plagiarism using software like Turnitin. Turnitin is the leading company in plagiarism detection software.

Institutions make use of plagiarism checkers, and you can too!

How do plagiarism checkers work?

Plagiarism checkers compare your document to a database of existing texts. The plagiarism software searches for similarities and highlights passages that contain potential plagiarism.

Not all plagiarism checkers are reliable. Where one plagiarism checker detects 2% plagiarism, another might detect 45% plagiarism.

The accuracy of plagiarism depends on two things:

  1. Database size
    Some plagiarism checkers only compare the uploaded document with web pages, while others also check books, publications and papers from other students.
  2. Plagiarism algorithm
    Most plagiarism checkers are only capable of detecting exact similarities. However, if the sentence structure is changed, if synonyms are used or if two sources are combined, most plagiarism checkers won’t detect the plagiarism.

Which plagiarism checker should I use?

You can choose between many free and paid plagiarism checkers. Before you decide to use a plagiarism checker, you should pay attention to these elements:

  • How much plagiarism it can detect
  • The price—many claim to be free but only offer a very limited free trial
  • Privacy and safety—some plagiarism checkers sell your document

At Scribbr, we tested all the popular plagiarism checkers to answer these questions. We made two comparisons: the first compared plagiarism checkers that claim to be free, and the second compared both free and paid plagiarism checkers.

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.

Open Google SlidesDownload PowerPoint

Frequently Asked Questions

Is paraphrasing considered plagiarism?

Paraphrasing without crediting the original author is considered plagiarism and therefore has serious consequences.

However, if you do credit the original author correctly using an in-text citation or footnote citation and include the full source in the reference list, then you do not commit plagiarism.

In order to avoid plagiarism, you must always cite the source in the correct citation format; otherwise, you are presenting something as your own work, even though it’s not.

The difference between paraphrasing and plagiarism

Can you plagiarize yourself?

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

You can plagiarize yourself by, for instance:

  • Submitting a document you previously submitted for a different course
  • Using a section of 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.

Read more about self-plagiarism

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).

What happens if you plagiarize?

The consequences of plagiarism vary depending on the severity of the infraction. Some types of plagiarism, such as direct plagiarism, are more serious than others, such as self-plagiarism.

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, the consequences are more serious. Aside from the fact that plagiarizing seriously damages your reputation, you might also lose your research funding and/ or your job.

Plagiarizing is a serious offense, and knowing how to avoid plagiarism is therefore important. Read more about the consequences of plagiarism and use a plagiarism checker to detect plagiarism yourself.

Checklist: Plagiarism prevention

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