Plagiarism and Common Knowledge

Plagiarism occurs whenever a source of information that is not common knowledge or personal opinion is not being given credit.

What is common knowledge?

Information such as dates, historical events, or concepts that any educated person knows, or that can be found in multiple general reference sources. For example, the year the Berlin Wall fell is something considered part of common knowledge as this information can be found in multiple reference books. However, an author's interpretation of the reasons why this historical event happened needs acknowledgement of the source. The criteria for common knowledge is that, whenever there is doubt, it is always better to cite.

Example 1: Common Knowledge - Correct Use

Student's Version

America was attacked on September 11th, 2001 when four planes were hijacked, two of them hit the World Trade Center in New York, one hit the Pentagon in Washington DC, and the last one fell in Pennsylvania. Perhaps the most shocking image was when the twin towers collapsed, leaving thousands of people dead in New York.


  • Note that the student is just mentioning a historic event that is common knowledge.
  • No citation of the source is necessary.

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