When you use somebody else's intellectual property - that is, any words, ideas, or images that you do not create yourself - you will need to give credit to the owner of said intellectual property. For research purposes we call this citing your sources.
When you cite your sources, you acknowledge the origin of the information. This lends credibility to your work by exhibiting evidence of your research and demonstrates the authenticity of your information sources. Your citations should be thorough enough that the reader can locate the same information you used in your research.
Chicago style has two variations: the notes and bibliography system, often used in humanities fields such as literature, history, and the arts; or the author-date system, used in the sciences and social sciences. For examples on how to cite: http://www.chicagomanualofstyle.org/tools_citationguide.html
MLA is used in some humanities disciplines, typically variations of language or literature in English or foreign languages.
Bibliographical Citation Software
Citation management software can make your researching and writing process a lot easier. There are several options for online software that will collect and format the citations you use. When automatically generating citations, however, always make sure to double-check that information before you submit your assignment.
Catholic University recommends these citation management software programs: