This system is most commonly used in the Humanities and Arts.
As the name suggests, the Notes and bibliography system uses footnotes or endnotes (or both) usually in combination with a bibliography. The notes allow space for describing unusual types of sources. Notes also provide the opportunity for adding comments on the sources where this might interrupt the flow of the paper.
A shortened note format can be used in place of full footnotes or endnotes as long as all items are included in the bibliography. For most student papers this will be the preferred method. The shortened note provides limited citation details and directs the reader to the bibliography. However, certain types of items, such as websites and social media, will be cited in full in the notes, and will not be included in the bibliography. For more detail on when and how to use shortened notes, see section 14.19 of the Chicago Manual.
Notes and Bibliography Quick Guide from the Chicago Manual of Style.