In short: Plagiarism is presenting someone else's work, words or ideas as your own without proper credit — and it includes reusing your own work without citation. Understanding the types below, and citing carefully, keeps your work original and your reputation intact.
What is plagiarism?
Plagiarism is using another person's words, ideas, data or images without appropriate acknowledgement. It is one of the most serious breaches of publication ethics and can lead to rejection or, after publication, retraction.
The main types
Verbatim (direct) plagiarism
Copying text word-for-word without quotation marks and a citation.
Mosaic (patchwork) plagiarism
Weaving together phrases from several sources, or changing a few words while keeping the original structure, without crediting the sources.
Paraphrasing without attribution
Restating someone else's idea in your own words but failing to cite them. Paraphrasing still requires a citation.
Self-plagiarism (text recycling)
Reusing substantial portions of your own previously published work without citing it or disclosing the overlap. Cite your earlier papers as you would anyone else's.
Redundant or duplicate publication
Publishing the same study, or largely the same data, in more than one journal without disclosure.
Image and data plagiarism
Reusing figures, tables or datasets without permission and citation, or manipulating images inappropriately.
How journals detect plagiarism
Journals run submissions through similarity-detection software that compares the manuscript with a large database of published work. Crucially, a human editor interprets the result: a similarity score is a signal to look closely, not an automatic verdict. Overlap in properly quoted and cited material, or in standard methods wording, is judged very differently from overlap in original arguments or results. Authors are expected to ensure their work is original and properly cited; manuscripts are checked for similarity as part of our editorial screening (see our plagiarism policy).
How to avoid plagiarism
- Cite every source of words, ideas, data and images.
- Quote directly — with quotation marks and a citation — when using exact wording.
- Paraphrase properly — express the idea in your own words and cite the source.
- Cite your own prior work and disclose any overlap to the editor.
- Manage references carefully with a reference manager to avoid accidental omissions.
- Obtain permission for third-party figures and reused material.
Key takeaways
- Plagiarism includes verbatim, mosaic, paraphrasing, self-plagiarism, duplicate publication and image reuse.
- You can plagiarise your own work — cite it and disclose overlap.
- Journals screen for similarity, but a human editor interprets the result.
- Cite, quote and paraphrase properly to keep your work original.