The UNC Honor System defines plagiarism as "the deliberate or reckless representation of another's words, thoughts, or ideas as one's own without attribution in connection with submission of academic work, whether graded or otherwise"
(Instrument of Student Judicial Governance, Section II.B.1.).
Plagiarism occurs when you intentionally or unintentionally use the words or ideas of others without properly acknowledging the source where you found the information.
Even if you find information online or from an electronic resource, you must avoid plagiarism just as if you were using print resources.
When you use the work of others and do not cite the source, you are committing a form of academic dishonesty, even if the assignment is not graded.
UNC does not treat the offense of plagiarism lightly; if a violation occurs, the punishment may include one semester of suspension and a failing grade in the class.
Common knowledge is information that is widely known and accepted by many people. The use of such information without citation does not constitute plagiarism.
Common knowledge can be easily located in a number of sources and usually cannot be disputed. For example, historical dates and facts are common knowledge. The statement "Abraham Lincoln was the 16th President of the United States" is a historical fact that cannot be disputed. Even if you used an encyclopedia to locate this fact, citation would be unnecessary.
Common knowledge may differ from one academic field to another. Established principles in a profession may be considered common knowledge within that particular field of study.
In a health-related article, researchers working in medicine and health affairs could name tobacco as the leading cause of preventable death in the US without a citation because this fact is common knowledge in their field. However, a first-year health sciences student may not know this statistic and would need to cite the source of the information.
"Tobacco use is cited as the leading preventable cause of death in the United States, making tobacco prevention an essential health priority."
Sentence from Smith, B. N., Bean, M. K., Mitchell, K. S., & Speizer, I. S. (2007). Psychosocial factors associated with non-smoking adolescents' intentions to smoke. Health Education Research, 22(2), 238-247.
In this health-related article, the author, a researcher, may make such a statement without citing a source. However, a first-year health sciences student may not know this statistic and would need to cite the source of the information.
When in doubt about whether or not information is common knowledge, CITE YOUR SOURCE.
No. Even though posters might not seem as formal as papers, you still must include your sources.
No. The information may be public, but it still isn't your original work, so you must properly attribute the author.
Yes. It doesn't matter if you aren't producing anything written. Any time you use someone else's work, you still must cite it.
Yes. This is considered common knowledge, so you do not have to cite your source. However, if you are in doubt, it's better to cite a source that you didn't have to cite than to leave out a source you should have cited.