Other forms: parasitisms
Parasitism is a relationship between two things in which one of them (the parasite) benefits from or lives off of the other, like fleas on your dog.
Parasitism and its root, parasite, come from para-, meaning "beside" or "next to," and sito, meaning "bread or food." There is parasitism in plant life, like the kudzu vine that grows on trees. We also talk about social parasitism, when someone lives at the expense of someone else. Some people think that government programs such as welfare or corporate grants and tax breaks are a form of parasitism.