Chicago style is commonly used in the Humanities, History, Business, and some Social Sciences. There are two options within Chicago:
Notes-Bibliography Style (NB), which uses footnotes and/or endnotes, typically followed by a bibliography
Author-Date Style, which uses in-text parenthetical citations of author(s) last name, publication year and pages, followed by a bibliography.
Here is a Citation Quick Guide for Chicago both NB and Author-Date.
Additionally, the Purdue Online Writing Lab has an overview of both Chicago styles
