(Greek/Latin - Authenticity, Reliability, Believability) Authenticity means realism or realistic in the original sense of the definition.
An authentic story is understood as a Film version of a story that is plausible in reality. Not a true story (in contrast to, e.g. a Science-Fiction story.)
The main film genres include: Action, Adventure, Comedy, Crime, Documentary, Drama, Family, Fantasy, Horror, Musical, Mystery, Romance, Science Fiction, Sport, Thriller, War, Western.
Based on true events or based on a true story.