something generally known to everyone

Something that is widely known. If you know it or can repeat it without looking it up in an information source, it is probably common knowledge.

information that does not need to be cited your paper because it is generally known An example of common knowledge would be an established fact. e.g. 'The year has 365 days'. 'John F. Kennedy was the 35th president of the United States. He was assassinated in 1963.'