There is some difference of opinion over how much credit must be given when preparing a newspaper article or historical account. Generally, reference is made to original source material as much as possible, and writers avoid taking credit for others' work.
Plagiarism should not be confused with copyright infringement, which is using another writer's work with or without full acknowledgement in a way that violates the exclusive legal rights granted to the author by copyright law.
The use of mere facts, rather than works of creative expression, does not constitute plagiarism. It does not matter whether the facts come from public domain or copyrighted works. However, the issue of public domain works versus copyrighted works is irrelevant to the concept of plagiarism. For instance, it is legal for a student to copy several paragraphs (or even pages) of text from a public domain book, such as Lewis Carroll's Alice in Wonderland, and then directly add these quotes to his or her own paper. However if these quotes were not clearly identified as to his or her source, then the student would be guilty of plagiarism, using another writer's work as if it were his or her own. High Schools, Colleges and Universities are especially sensitive to this kind of academic dishonesty, as many students claim that if an action is legal, it must be ethical. This is untrue. All high schools, college and universities have academic codes of ethics which prohibit all forms of plagiarism, whether the idea is plagiarized from public domain or copyrighted sources.
Similarly, it is plagiarism to steal the specifics of someone else's novel idea, and then present it as one's own work. This type of plagiarism is rampant in high schools, colleges and universities, when students illicitly use the analyses in "Cliff's Notes", and falsely present them as being their own original analysis.
According to some academic ethics codes and criminal laws, a complaint of plagiarism may be initiated or proven by any person. The person originating the complaint need not be the owner of the plagiarized content, nor need there be any active or passive communication from a content owner directing that any investigation or discipline process be initiated in response to the plagiarism.
It is not plagiarism when two (or more) people independently come up with the same idea or analysis.
Famous examples of plagiarism: