When conducting your research for a paper, speech, etc....make sure you keep track of where you get your information from! You will need to cite these sources to show where you got the information from and to give credit to the author.
There are different styles used to cite your sources. Depending on your class and instructor you might be asked to cite your work APA, MLA, or Chicago Style (and others). Make sure you ask your instructor what style they want you to use.
The differences between the styles is the way and how you put the authors name, title, year of publication, volume, isssue, etc...
MLA Handbook by 
Publication Manual (OFFICIAL) 7th Edition of the American Psychological Association by 