APA style was developed and is maintained by the American Psychological Association (APA). It is heavily used by the social sciences, behavioral sciences, and many other disciplines.
Features: Focuses on dates the study was published; page numbers may also be cited. Features in-text parenthetical citations of author(s) and date: (Smith, 1998). A page number also must be added for quotes taken from a specific page: (Smith, 1998, p. 123). Endnotes or footnotes may be used to add supplementary comments.
Citation manual: Publication Manual of the American Psychological Association.
All examples below are based on examples from the 6th edition.