Depending on the class, your professor will tell you to use different 'citation styles' to cite your research sources (that is, to create a bibliography of the books, articles, government documents, web pages, etc. which you have used for a paper or project). There are many styles of citation used by different disciplines, including MLA or APA styles with which you may be familiar from high school.
Academic disciplines often use the citation style of their 'core' journals. For instance, chemists most often use the style of the American Chemical Society journals. Generally speaking, use the citation style required by your professor. Whatever style you use, remember that RefWorks can help you cite in correct format! Click here for more information on RefWorks.