Common knowledge means information that does not belong to any one individual and can be verified in many different places. Common knowledge is facts, dates, events, information or concepts that belong generally to an educated public. Common knowledge is information that is freely available and was not produced as the intellectual property from the work of individuals
Some examples of common knowledge:
Caution: Just because something is on the Internet doesn't mean it is "common knowledge." Most information on the Internet is someone's intellectual property.
When you use someone else's language word for word, you indicate this in a quotation. You must attribute the quote to the original source.
Putting a passage from a source into your own words is paraphrasing. This also must be attributed to the original source.
Summarizing is putting the main ideas of a source in your own words. Summarized ideas must also be attributed to the original source.
For help with paraphrasing and quoting