Citing your sources means giving credit to the authors whose information you use when writing a paper. Generally, there will be two parts to this process: (1) a short notation in the text of your paper called an in-text citation and (2) a list at the end of your paper that includes complete information about each source you used. This list is called your "Works Cited." You must cite the source of any idea you borrow, whether you put the idea in your own words ("paraphrase" it), summarize it, or quote it word for word. Failure to give credit to your sources is called plagiarism and can result in lowered grades or more severe consequences.
There are a variety of formats or citation styles, which outline different, very specific, ways to list the title, author, date, and other information of each source you use in writing your paper. MLA is one of those styles often used at Martin.