Horror films take our deepest fears, those ideas and thoughts that are just so scary that we can't contemplate them becoming real, and ask the question "What if?" The fear of the unknown has to be the strongest human emotion and a good horror film can make us feel like we are experiencing our worst nightmare.
In my opinion, the human imagination will always be able to out do any special effects and it is the suggestion of something terrifying that really scares us. Like in Jeepers Creepers - this film really scared me until we finally saw the monster in his winged hell-beast glory. It was the same with Stephen King's IT - he just wasn't scary when you saw him for real (clowns are infinately more scary than massive beast things). Don't get me wrong, if I encountered Mr Jeeper Creeper or IT, I would be scared witless, but on screen it stopped being so terrifying.
Deep down, I know that monsters like that don't really exist and seeing the monsters in a film reinforces the fact that it is just a film. It's like lying awake in the dark feeling like there is something in the room with you even though you know it is not possible. I woke from a nightmare once to feel breathing on my face - I just knew that a terrifying monster was right there and, if I opened my eyes, he would be nose to nose with me, ready to bite my head off. I kept my eyes shut until I fell back asleep. My imagination had managed to scare me half to death without there ever needing to be a monster on my bed.
A film that can unsettle us, invoke our deepest fears and revulsions, without relying on blood and gore will always be good. A splash of blood across someone's face and the look of complete terror in their eyes is far scarier than seeing the actual scene of horror which they have just witnessed. Films that can maintain realism are far better than those with a massive body count, liters of blood splashed all over the place, and some monster with supernatural powers that just doesn't ever die. Films that leave me feeling unsettled at the end are better than those where the skinny heroine in a cut-off tee and tight jeans suddenly reveals her Kung Fu training to kick the monster's head off, after which she utters some ridiculous line like "I guess its just that time of the month" ( What, exactly, is wrong with running away, crying like a girl?). The fear of something terrifying occurring in a normal setting, to normal people will always scare me more than a contrived horror film that relies on shocking us more than the last film and forgets about the plot.
