The main objective of a horror film is to scare and terrify its viewer. In able to achieve this objective a film must use conventions from the horror genre. Without these conventions, a horror film would not be horror.
conventions:
Mis-en-scene-iscolates settings, dark atmosphere, shodowy lighting.
Camerawork and editing- fast cutting for violent action, point of view shot to make the viewer see what the killer sees, hand held shots.
Music and Sound- heartbeat, heavy breathing, screams, echoes.
Icons- blood, shadows, masks, ghosts, knives.
Narrative Structure- Todorov's narrative theroy- equilibrium, distruction, restoration of equilibrium, Propps character theory, binary oppositions between good and evil, final girl theory- victim ( strong smart character) survives/ overthrows the murderer.