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You're probably familiar with books and know they can be about anything, real or imagined.
Novels and short stories are examples of "imagined" works or what is called Fiction. An author creates events and characters in fiction, even though similar events may have actually taken place and similar people may have existed or exist.
Non-Fiction books deal with factual information, and would be the type used for a research paper. Examples include reference books like endydlopedias and dictionaries, history, literary criticism, and science books.