Plagiarism is using someone else's work without crediting the original author or creator. This includes the use of any ideas, research, or analysis of a topic, that were written by someone else, even if you have not used their exact words.
Obvious examples of plagiarism are copying and pasting parts of an article or online encylopedia essay into your own paper. However, even the accidental omission of a citation for a source is regarded as plagiarism.
No one has ever failed a class for using too many citations, however you could fail a class, or even be expelled, for failing to cite the sources you have used.
For more information on these concepts, see the guide Ethical Use of Information.
To acknowledge the work and words of others is fair play in life. Moreover, the ethical use of information is a cornerstone of university-level research and the scholarly process. Explore the tabbed pages above for some basic information about this topic, along with links to library materials and external websites that provide further information.
Most of the materials in this guide help those using materials created by others comply with copyright. However, some of the materials will also be of interest if you are the creator of information content and artistic works.
This guide is not written by a copyright lawyer and should not be seen as a legal document. The author of this guide is also NOT the instructor of your course. So if you are writing a paper and have questions about fair use and proper documentation, your professor should be your final arbiter.