Plagiarism is described in the W&L 2019-20 Catalog, and cited by the Student Executive Committee, as "the use of another's words, figures, or ideas without proper ackowledgement." The resources listed here should be considered reliable sources of advice about what constitutes plagiarism and how to avoid it.
Unfortunately, there is no universally agreed-upon "style" for documenting the use of sources in research -- no single method for formatting footnotes, bibliographies, endnotes, in-text citations, etc. Instead, there are more than a dozen, most of which are specialized for use in one or more subject areas. The W&L University Library maintain a collection of resources on these styles:
A journal article's literature review discusses the existing research on aspects of the topic.