It combines elements of:
* Science fiction: The story features an alien invasion and a unique concept of a "host" body being occupied by an alien entity.
* Romance: The central plot revolves around the developing relationship between the human host, Melanie, and the invading alien, Wanderer.
* Paranormal: The alien entity, Wanderer, possesses supernatural abilities, adding a paranormal aspect to the story.
Therefore, while it is difficult to categorize it into just one genre, "The Host" can be best described as science fiction romance with paranormal elements.