In fact, there are a lot of layers to a horror film and even more lenses through which to look at one. By taking a look at the trends, content, and techniques used in horror, we can learn a lot about the culture we live in, societal fears/anxieties/morays, technological advances, the state of world politics, and even a whole hell of a lot about ourselves, both on an emotional and biological level.
I spent five years of college studying horror film, but I still know I barely scratched the surface of the genre. However, if you're looking for a good primer, this infographic provides a truly great introduction into the anatomy of a horror film. It touches on everything from the use of sound, the kinds of camera angles that are most often used, archetypal horror characters, and even the effects horror has on us emotionally and biologically.