The APA citation was developed by the American Psychological Association for use in its own publications, but over the course of time it has gained popularity that rivals the esteem and reputation of the Modern Language Association (MLA) citation style. As a matter of fact, APA is today the standard style in more than a few social and health-related circles. Fields that widely accept and use the APA citation style include but are not limited to criminology, nursing, psychology (of course), sociology and social work, business, and economics.
Only the first word of a title or subtitle, and proper nouns, are capitalized in book, magazine, journal, and article title citation in the APA style. As distinguished especially from the MLA citation style in which full forms are used to depict all the names of authors of a piece of cited work, the APA style defers to full forms only for last names while initials are used for middle and first names. However, all author names are written and still written in last-first order in the list of References, e.g., Smith, N. If there happens to be more than one author on the cited work, names are then separated by commas while an ampersand (&) precedes the final name, e.g., Smith, N., Armstrong, W., & Bauer, J.
Someone writing and citing references the APA style always has to include the year of publication of the cited work both in the list of references and in the in-text citations. In addition, if they are including citations from an online resource, they would have to include the date on which the source was retrieved from the Web. Also, with the APA Style, page numbers for a particular section or work referred to in a piece are included in the list of References, although not in the in-text citation. Page numbers may only be waived when it comes to electronic sources that do not display page numbers – journal articles and printable documents do not fall into this category.
This is only the tip of the iceberg, but it may serve for the casual canvasser; there is a lot more that the APA citation style involves, but more on these may only be obtainable from the APA publication manual or the official website of the American Psychological Association.