Information does not need to be cited if it is what is known as common knowledge. Common knowledge is information that most people know. It can differ by culture or field, so use your judgement. Use these questions to help you decide if a piece of information is common knowledge:
- Would the average person accept the information without having to look it up? (probably common knowledge)
- Would you likely be questioned on where you got the information? (probably NOT common knowledge)
- Does the information include specific dates, statistics, datasets, or information from a study? (NOT common knowledge.)
When in doubt, CITE! It is better to be cautious than to accidentally plagiarize.
Adapted from What is common knowledge? by MIT.