The Online Writing Lab at Purdue University created an in-depth APA guide that is a trusted resources for many students and instructors.
APA Citations Examples from the Library at University of Maryland University College is another great option for looking up APA formatting for specific references you are citing.
The APA makes an effort to keep their manual up to date. In between editions, however, new information sources emerge. This APA blog fills in the gap. Search its contents to see how you should cite Twitter, Facebook, and a host of other new media or unusual sources.
On their website, the APA explains why adopting and following a documentation style matters as follows:
To achieve this clarity of communication, publishers have developed rules of style. These rules are designed to ensure clear and consistent presentation of written material. Editorial style concerns uniform use of such elements as
When editors or teachers ask you to write in APA Style®, they are referring to the editorial style that many of the social and behavioral sciences have adopted to present written material in the field.