Plagiarism is the "wrongful appropriation" and "stealing and publication" of another author's "language, thoughts, ideas, or expressions" and the representation of them as one's own original work.
Plagiarism is considered academic dishonesty and a breach of journalistic ethics. It is subject to sanctions such as penalties, suspension, expulsion from school or work, substantial fines and even incarceration. Recently, cases of "extreme plagiarism" have been identified in academia. The modern concept of plagiarism as immoral and originality as an ideal emerged in Europe in the 18th century, particularly with the Romantic movement.
Plagiarism is not in itself a crime, but like counterfeit can be punished in a court for prejudices caused by copyright infringement, violation of moral rights, or torts. In academia and industry, it is a serious ethical offense. Plagiarism and copyright infringement overlap to a considerable extent, but they are not equivalent concepts, and many types of plagiarism do not constitute copyright infringement, which is defined by copyright law and may be adjudicated by courts.
The reuse of significant, identical, or nearly identical portions of one's own work without acknowledging that one is doing so or citing the original work is sometimes described as "self-plagiarism"; the term "recycling fraud" has also been used to describe this practice. Articles of this nature are often referred to as duplicate or multiple publication. In addition there can be a copyright issue if copyright of the prior work has been transferred to another entity. Self-plagiarism is considered a serious ethical issue in settings where someone asserts that a publication consists of new material, such as in publishing or factual documentation. It does not apply to public-interest texts, such as social, professional, and cultural opinions usually published in newspapers and magazines.
In academic fields, self-plagiarism occurs when an author reuses portions of their own published and copyrighted work in subsequent publications, but without attributing the previous publication. Identifying self-plagiarism is often difficult because limited reuse of material is accepted both legally (as fair use) and ethically.