Chicago style is mostly used in the arts, humanities, social sciences. It has two different systems:
If you aren't sure which system to use, check with your course instructor.
Turabian style is a student- and researcher-oriented version of Chicago style. The two manuals have some differences (e.g., formatting a paper), but the citation styles are the same. If you need to cite sources in Turabian style, you can also use the Chicago citation guides.