Simply put, plagiarism is the use of someone else's work without giving credit, either intentionally or unintentionally.
Plagiarism is a serious offense. It can result in a failing grade for the assignment or even the course. For more details on possible consequences, see the Student Code of Conduct.
Copying word-for-word from a source without citing
Paraphrasing a source without citing
Patchwriting, or copying a section of a source and changing a few words, with or without citation
Copying and pasting from an online source without citing
Neglecting to use quotation marks around a direct quote
Importing photos, audio, or video without citing
Translating without citing the original source
Providing incorrect citation information about the source
Using a paper from the web (whether free or paid)
Using someone else's paper, even with their permision
Submitting the same paper in two classes, unless both teachers give permission
CITE YOUR SOURCES!
Cite information you have used from books, articles, online databases, and websites (even if the website does not have the copyright symbol displayed).
Cite interviews, speeches, TV programs, films, live performances, ads, works of art, and letters.
You do not need to cite "common knowledge" (information broadly known by persons in the field or the audience for your paper).
When in doubt, cite!