Common knowledge is information that is widely-recognized and is considered factual by scholars (experts in that field).
The easiest way to determine if something is common knowledge is to verify that the information has been used in at least five authoritative sources without citation. If those scholars did not cite it, then you do not have to cite it either!
Some examples of common knowledge include:
Remember: if you are not sure if it is common knowledge, cite it!
The Modern Language Association (MLA) Style Manual and Guide to Scholarly Publishing is the official style guide of Mountain View College.
Disciplines that use MLA include: English language, literature, and literary criticism, non-English languages, literature, and literary criticism, and cultural studies.
The American Psychological Association (APA) Style is most often used in social sciences (psychology, sociology, linguistics, economics, and criminology), business, and nursing.
Chicago/Turabian Style is most often used in fine arts (art, art history, music, and theater), anthropology, computer science, and history.