Genre is a way of organizing products into different categories, for example films can be ordered into the genres of horror, comedy etc. These categories all have similarities that run through a specific genre and differences between each genre, making them PREDICTABLE AND EXPECTED but also INNOVATIVE AND UNEXPECTED.
Genre is applied to all forms of media, including radio, TV, music etc.

“. . . saddled with conventions and stereotypes, formulas and
clichés and all of these limitations were codified in specific genres. This was the very foundation of the studio system and audiences love genre pictures . . .” – Scorcese, A personal Journey through American Cinema (1995) This quote shows that studios have specific genres that they stick to, creating the foundation for how films are made in each studio. Each of these genres have specific elements that the studios follow to create their films.