Authors working in the same field all use the same style guide when publishing their work. The style guide tells them how to write, how to format their pages, how to cite their sources, and more. Use of a consistent style allows readers to focus more on the content of article, and less on figuring out what the author really meant, or tracking down their sources.
Chicago Style Manual
The Chicago Manual of Style (CMS) is most commonly used to write papers and cite sources within the humanities.