We use citations and reference lists to guide the reader/viewer/audience to the sources used to create our paper, video, presentation, etc. It is common for individuals who want to learn more about a topic to use the sources in a reference list. Citing is a recognition of other people's work.
Chicago Style has two different formats Notes & Bibliography and Author/Date for in-text citing and the bibliography. Each use a slightly different format.
This style uses notes (footnotes or endnotes) together with a bibliography. Notes provide an author the option to add additional information or comments about a cited source.
The author-date system is similar to APA or MLA in that in-text citations are used instead of footnotes or endnotes.