There are many reasons why it is so important to cite the sources you use in your research.
The Chicago style is often used in the humanities and has two ways of citing:
(1) notes and bibliography and
(2) author-date.
Notes and Bibliography has sources cited through footnotes or endnotes in their writing and through bibliography pages. Author-date is similar to APA style, with in-text citations referencing the author and date. For example, (Jones, 1998).
Bibliography example of a citation from a journal article (notes & bibliography style):
MacDonald, Susan Peck. “The Erasure of Language.” College Composition and Communication 58, no. 4 (2007): 585-625.
Bibliography example of a citation from a journal article (author-date style):
Pape, Robert A. 2013. "The Strategic Logic of Suicide Terrorism." American Political Science Review 97 (3):343-361.