As defined by Merriam-Webster's Dictionary, to plagiarize is:
"to steal and pass off (the ideas or words of another) as one's own : use (another's production) without crediting the source : to commit literary theft : present as new and original an idea or product derived from an existing source." Source: https://www.merriam-webster.com/dictionary/plagiarize
All of the following are considered plagiarism:
turning in someone else's work as your own
turning in your own work multiple times in different classes (considered self-plagiarism)
copying words or ideas from someone else without giving credit
failing to put a quotation in quotation marks
giving incorrect information about the source of a quotation
changing words but copying the sentence structure of a source without giving credit
copying so many words or ideas from a source that it makes up the majority of your work, whether you give credit or not (see our "fair use" page for rules)
What DON'T you need to cite?
Common knowledge (e.g., the sun rises in the east and sets in the west).
Your own opinions or experiences.
Most cases of plagiarism can be avoided, however, by citing sources. Simply acknowledging that certain material has been borrowed, and providing your audience with the information necessary to find that source, is usually enough to prevent plagiarism.
The following diagram lists 10 types of plagiarism and poor practices that should be avoided. The top of the list represents the most severe with greatest intent to the least. The far right column provides focus areas to review for improvement. Types of plagiarism include: