APA style began in 1929 with a group of psychologists, anthropologists, and business managers who wanted a set of procedures that make their scientific writings uniform and easier to comprehend. As with most citation styles, APA has a set standards for "punctuation, selection of 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 a part of a manuscript" (Source: Official APA website) which must be followed.
Listed below are some common sources which show how to properly cite/format using APA style.
Organizing your Social Sciences Research Paper APA Format
The Basics of APA Style - a Tutorial
These FAQs will help clarify frequent areas of confusion when using APA.
Publication Manual of the American Psychological Association by