What is a film without a director? Every director, from Ava Duvernay to Chloe Zhao, has their own particular voice: a set of themes they repeatedly explore, their narrative and visual quirks, and even in some cases their preferred stable of actors to work with. This idea is neatly summarized in the notion of auteur theory, which categorizes a film director as the author of the movie (the term was popularized by the French film journal Cahiers du cinéma — “auteur” just means “author” in French).
Source: The Surprising Hollywood Rule Inspired By Clint Eastwood