APA (American Psychological Association) style originated in 1929, when a group of psychologists, anthropologists, and business managers convened and sought to establish a simple set of procedures, or style rules, that would codify the many components of scientific writing to increase the ease of reading comprehension.
As with other editorial styles, APA style consists of rules or guidelines that a publisher observes to ensure clear and consistent presentation of written material. It concerns uniform use of such elements as headings, tone and length, punctuation and abbreviations, presentation of numbers and statistics, construction of tables and figures, citation of references, and many other elements that are part of a manuscript (Source: Official APA website).
APA Style calls for three kinds of information to be included in in-text citations:
All of these pieces of information must match the corresponding reference list entry exactly!
Research has shown that "the demographic of the fly is a key determining factor in the robustness of its flavour" (Frog, 1998, p.33).
As stated by Frog (1998) in his seminal article, "the demographic of the fly is a key determining factor in the robustness of its flavour"(p. 33).
In this example, the author's name is mentioned in the text itself; therefore, the name need not be repeated in the bracketed citation.
Each in-text citation must be associated with an item in a comprehensive list of references at the end of your paper. Pay attention to your formatting when constructing your reference list; APA is particular about which components to capitalize, italicize, and which punctuation to use in a given situation.