Citations are meant to help the research process.  If you read an article, and the author mentions an idea he got from another author, you might want to read about that idea for yourself.  The citation helps you find the original source of the idea or quote.

Citation styles are taken from style guides or style manuals that have been created to help authors of books and articles to be consistent and comprehensive when writing for publication. 

The three styles used at DBU are:

APA - American Psychological Association

MLA - Modern Language Association

Turabian (Chicago) - from the University of Chicago; Kate L. Turabian wrote her manual to interpret the Chicago style for students writing theses and dissertations

Using style guides may seem like a lot of extra work, but when you stick to a particular style, you are less likely to leave out important details, like dates or page numbers, that can help your readers locate your sources. 

Your professor will probably tell you which style to use.  Check your syllabus or assignment guidelines if you're not sure.  In general, certain colleges have certain preferences:

College of Business: APA

College of Christian Faith: Turabian

College of Education: APA or MLA

College of Fine Arts:

Music: Turabian

Communications: APA

College of Humanities & Social Sciences:

English, History, Foreign Languages: MLA

Psychology, Sociology: APA

Political Science, Criminal Justice: APA

College of Natural Sciences & Math: APA or "scientific" MLA