APA referencing is the preferred style in psychology and is used to acknowledge sources, protect against plagiarism, and allow readers to trace information to its source. It requires including both in-text citations with author and date and a bibliography at the end listing all sources alphabetically by author regardless of format. The basic elements of an in-text citation are the author's surname and year of publication, and page numbers are included for direct quotes. Quotations, summaries, and paraphrasing all require citations, and a bibliography lists everything referenced in the assignment.