APA referencing is the author-date style of referencing described in the Publication Manual of the American Psychological Association. In this style, each reference consists of an in-text citation of the author and date, with the full details in the reference list at the end of the document.
The 2 parts to acknowledging reference material in the APA style work in partnership, to indicate to your reader where your ideas have come from and how they can locate the original source of these:
How to use this APA Referencing guide:
These reference formats examples are largely based on those provided in the APA Style Blog
The overarching principle is that readers should have a reference detailed enough to allow them to locate the original source if they wish. You should always acknowledge other authors whose ideas or information you have used.
For further examples see the APA Style website, or the Publication Manual of the American Psychological Association, 7th edition.