Plagiarism (from Latin for “kidnapper”) is the use of someone else’s words or ideas, including but not limited to textbooks, other literary works, documentaries, Web sites, radio broadcasts, magazines, newspapers, and/or personal interviews, you must cite the source internally (citations or footnotes); moreover, you must also provide full reference information at the end of the article or book, whatever the case may be.
It is not enough, however, to include merely a reference page. Again, you must include parenthetical documentation or footnotes; and it does not matter if one is paraphrasing (putting things into one’s own words), one still must let the reader know exactly where one learned the information, that is, unless something is considered common knowledge.
What is common knowledge? Common knowledge is information that the majority of people already know. For example, the majority of people know that George Washington was the first president of this country; they also know that Martha was his wife; but on the other hand, the majority of people do not know in what year Washington was born, where he attended college, or in what year he died.
Granted, common knowledge for one person may not be common knowledge for another person. For example, since I teach literature and I have been teaching the subject for years, what I know about this subject is considered common knowledge for me because it is knowledge shared by other instructors who also teach literature. However, the average person knows very little about literature; therefore, he or she should provide the source of ideas, facts, dates, etc. That is simply the way things work. Of course, a writer may be extremely well read and possess quite a bit of knowledge about a certain area of literature, but the reader has no way of knowing how much knowledge the writer possesses, so it is often in the writer’s best interest to locate a source and then cite that source in order to prevent any suspicion of plagiarism, however ill founded that suspicion might be on the part of the reader.
As it says in the APA Manual (2003), "Each entry in the reference list must be cited in the text" (p. 235). Moreover, "Whether paraphrasing or quoting an author directly, you must credit the source" (APA, 2003, p. 120).
Publication Manual of the American Psychological Association: Fifth Edition (2003). Washington, D.C. American Psychological Association, p. 120, 235