In addition to the general requirement to avoid plagiarism, there are two main purposes for citing information:
How you cite information in your paper is important, but before you start you need to understand what type of information should be cited and to gather the needed information from each source that you use as you go along so that you don't have to go back and find it later. To fulfill the purposes for citing information, your citations need to be accurate and complete, and you will usually need to gather the following information:
The most commonly used citation styles are APA, MLA, and Chicago, although there are many others that are used for certain subjects or circumstances. Your professor will tell you which style to use for an assignment.