Here's a breakdown:
* Parasitism: One organism (the parasite) benefits by living in or on another organism (the host), causing harm to the host.
Important note: Parasitism doesn't always involve killing the host. The goal of the parasite is often to sustain itself and reproduce, not to kill its host. Killing the host would ultimately harm the parasite as well.
Let me know if you'd like more examples of parasitic relationships!