Plagiarism and self-plagiarism: differences and prevention

What plagiarism and self-plagiarism mean

Plagiarism occurs when you present another person's words, ideas, or images as your own. It may be deliberate or result from careless note-taking, but either way it withholds credit from the original creator and prevents readers from tracing the source.

Self-plagiarism occurs when you present your own previously published work as new. In student work, some institutions apply the same principle to an assignment submitted in another course without permission. Although the author has not changed, readers or institutions still need to know which material already existed and what the new work contributes.

Accurate citation is part of academic integrity. You must also follow your institution's policies and, when reusing protected material, any applicable permission or licensing requirements.

When to credit a source

Give credit when you:

• paraphrase an idea;
• reproduce exact wording;
• use data or a data set;
• reproduce or adapt a table, figure, or image;
• use another person's theory, method, or explanation;
• reuse content from your own previously published work.

An ordinary citation generally provides attribution for an idea or paraphrase. Reproducing images, tables, tests, or long passages may also require a copyright attribution or permission. Citation and permission address different responsibilities.

Common forms of plagiarism

Copying without marking the exact words

When you reproduce a sentence, use quotation marks or block formatting and add a locator. Changing one word or removing part of a sentence does not turn it into a paraphrase.

Incorrect:

Reviewing in stages reveals problems that the first reading allowed to pass unnoticed (Rojas, 2023).

If that sentence preserves Rojas's words, the citation alone does not show that it is a direct quotation.

Correct as a direct quotation:

Rojas (2023) wrote that “reviewing in stages reveals problems that the first reading allowed to pass unnoticed” (p. 42).

Paraphrasing without a citation

Writing an idea in your own words does not make it your idea. A proper paraphrase retains the author and year.

Staying too close to the original

Replacing a few words while keeping the source's structure creates writing that is too close to the original. Understand the idea, write without looking at the passage, and compare the two versions afterward.

Using images or data without attribution

Photographs, graphs, tables, and data sets also have creators. An image being available online or carrying an open license does not make it your own. The figures guide explains how to identify its source.

Inventing citations or references

A source must exist and support the claim where it appears. Fabricating authors, titles, or publication details creates false evidence and violates academic integrity.

When self-plagiarism occurs

Self-plagiarism occurs when a substantial part of your earlier work is presented as new without explanation. In scholarly publication, presenting the same data or ideas as separate research efforts can distort the available evidence.

In student work, an institution may consider it self-plagiarism to submit the same paper in two courses without permission from the current instructor. Reusing part of an earlier assignment in a thesis or larger project may be allowed, but you should discuss it with your instructor or adviser and follow institutional policy.

Example of transparent reuse

When you need to return to an explanation from your own published article, introduce the relationship and cite the earlier work:

An earlier analysis explained that reviewing content and formatting separately helps writers focus on different decisions (Rivas, 2022). The present paper applies that distinction to collaborative writing.

The citation marks the idea that was already published, and the second sentence presents the new contribution. The details are illustrative.

APA Style does not set a universal amount of your own text that may be repeated without review. When reuse is substantial, ask the instructor, adviser, editor, or other responsible authority before submitting the work.

How to prevent plagiarism while writing

1. Record each source while reading. Save the author, date, title, and exact location of any passage you may quote.
2. Separate your notes from copied wording. Put quotation marks around transcribed sentences in your notes.
3. Add citations while drafting. Do not leave every author and year until the end.
4. Compare citations and references. Every recoverable cited work needs its full reference.
5. Review each paraphrase. Make sure it does not repeat the original structure or distinctive wording.
6. Ask before reusing earlier work. Permission depends on the assignment and institutional policy.

A similarity tool can identify matching text, but a match alone does not establish plagiarism. It may also flag titles, references, or correctly presented quotations. A reviewer must consider how each passage was used and credited.

Checklist

Before submitting, check that:

• every borrowed idea has clear attribution;
• exact wording appears in quotation marks or a block;
• paraphrases include an author and year;
• images, tables, and data identify their source;
• no citation or reference was invented;
• you explained and cited any reuse of your own publication;
• you obtained permission before resubmitting student work;
• citations and references correspond.