For the most part, any ideas, information, or language you borrow from a source—whether the source is in print or online—must be acknowledged by including an in-text citation and an entry in your list of works cited (MLA style) or references (APA style). The only types of information that do not require acknowledgment are common knowledge (for example, John F. Kennedy was assassinated in Dallas), facts widely available in many sources (U.S. presidents used to be inaugurated on March 4 rather than January 20), well-known quotations (“To be or not to be /That is the question”), and material you created or gathered yourself, such as photographs that you took or data from surveys that you conducted.

Remember that you need to acknowledge the source of any visual (photograph, table, chart, graph, diagram, drawing, map, screen shot) that you did not create yourself as well as the source of any information that you used to create your own visual. (You should also request permission from the source of a visual if your essay is going to be posted online without password protection.) When in doubt about whether you need to acknowledge a source, do so.

The documentation guidelines in the next two chapters present two styles for citing sources: MLA and APA. Whichever style you use, the most important thing is that your readers be able to tell where words or ideas that are not your own begin and end. You can accomplish this most readily by taking and transcribing notes carefully, by placing parenthetical source citations correctly, and by separating your words from those of the source with signal phrases such as “According to Smith,” “Peters claims,” and “As Olmos asserts.” (When you cite a source for the first time in a signal phrase, use the author’s full name; after that, use just the last name.)