Chicago style is usually used in the Humanities, History, and other fields. It includes several different versions for notes, bibliography entries, and shortened citations.
Turabian style is a simplified version of Chicago style with some modifications for the needs of student writers. It includes a notes-bibliography style and a parenthetical citations-reference list style.
There are several versions of Chicago style, including Turabian style, which is a simplified version keyed toward students. Humanities disciplines frequently make use of the Notes and Bibliography system (NB), which allows writers to make footnotes and other commentary. Social sciences disciplines tend to use the Author-Date system.
The Notes and Bibliography system requires that each in-text reference includes a number corresponding to a footnote.
From the Purdue Owl site:
More information on Notes and Bibliography citation lists: Purdue OWL guidelines for Chicago Manual of Style 17th Ed.
In the Author-Date system, citations are placed into parentheses in the text in this order: author last name year of publication, page number, and then fully cited in the References section.
More information on Author Date system: Chicago Style Information from Trinity University
Scroll down for more instructions on References from the Purdue OWL site.
Examples are for Bibliography, using Notes-Bibliography style. See references to the left for more information on other styles in Chicago.