Although there are many other academic formats, APA is perhaps the most common. It is frequently used by "researchers in education, social work, nursing, business, and many other behavioral and social sciences" (American Psychological Association). Hence, students in those subjects are commonly required to use this format.
"APA style" refers to the rules presented in the Publication Manual of the American Psychological Association, or the APA.
The American Psychological Association began setting standards for research paper format and citations (as well as primary research methods and ethics, general use of language, and style of writing) in order to help scholars all over the world follow coordinated guidelines. Standardized papers are easier to read, understand, compare, and study. Since researchers often build upon past studies, these guidelines help make that progress smooth.
APA style is also used in many scholarly journals. To submit an article to a journal, the writer must follow APA format. Accordingly, the writer can format his article in one method and then send it to many journals, since they all follow the same rules. Additionally, the journal publishers don't need to spend time changing articles into their particular formats; instead, all submitted articles must already follow the journals' style.
Even if you're in college and not a professional primary researcher, following APA style is useful. Perhaps most importantly, the APA citation rules will ensure that you record all essential information about your sources, quote or cite all non-original information properly, and thereby avoid plagiarizing the information you have researched.
APA style can help you in other ways, too. For example, following rules about spacing, margins, font type, and font size can help you ensure that your paper is the proper length. (If you wrote a single-spaced paper, even though APA uses double spacing, then you might write a paper twice as long as necessary.) Standard formatting also helps your professors grade papers more easily and quickly. And ultimately, if your professor requires APA style, then using APA in your research paper will help you get a good grade.