Looking for more in-depth guidance with citations? Check out Calvin's Rhetoric Across the Curriculum: Writing with Integrity website, which includes very useful advice, from an explanation of why citation matters to examples of how to correctly document sources using the major citation styles.
Your professor will usually specify the citation style required for your paper or project. Always check with her or him about any specific questions regarding expectations and requirements. Some general guidelines, though:
MLA style - typically used in the Humanities (e.g., English)
APA style - used for Social Sciences (e.g., Psychology, Sociology)
Chicago style - used in History; also, a version of Chicago style, Turabian, is often used in Calvin Religion and Seminary courses
The Rhetoric Across the Curriculum website offers electronic links to sample citations in all these styles.
Citation generators are online tools that create your citations for you (you just need to enter the information). Most library research databases include their own citation generators (look for a link such as "Cite This"), and Microsoft Word also offers this feature (look in the References tab). Some other free citation generators on the web include:
As of Spring 2016, MLA has released a new (8th) edition of its style manual, with a new approach to citation and new rules. To find out what's different, check out these resources:
From Marquette University Libraries, this short (4-min) video also provides a useful introduction:
MLA, APA, and Chicago (or Turabian) styles are the most common documentation styles required by Calvin professors. The rules and guidance for these styles are provided the manuals listed below, which can be found on the 2nd floor (in Print Reference and at the Research Assistance Desk). Also linked are online guides or help from the manuals' style editors.
Note that a number of online citation generators now exist on the web, but they are not always correct nor cover every situation. The style manuals are considered the authorities for citation and formatting rules.
There are many, many online sources of citation guidance, but the Purdue Online Writing Lab (OWL) is a very dependable go-to resource.