When we use another person's idea in our research, we must include a brief notation next to that idea to let our readers know who developed it. This brief notation is called an in-text citation. At the end of our work, we include a fuller notation, which provides details that allow others to identify and locate the source in which we found that idea. This fuller notation is referred to as an end-of-paper citation.
Which details must be included within these in-text and end-of-paper citations, and how each is formatted, depends on the citation style we have been asked to use.
For example, end-of-paper citations are listed on the last (usually separate) page of the paper. In APA style that page is titled "References." In MLA style that page is titled "Works Cited."
Each citation style has different rules about how in-text and end-of paper citations for various source types (books, articles, web pages, videos) and situations (online, print, no author, multiple authors) must be constructed (what is included, and in what order) and formatted (punctuation, italics, capitalization).
There are thousands of citations styles, but APA and MLA are the two most commonly used in college research writing. Each style also has formatting rules for the paper itself, including title page rules, font size, section headers and so on.