1. Predation (where one organism kills and eats another organism; predator and prey)
2. Competition (where species compete for a particular resource, even without coming in contact with each other)
3. Paratism (where a parasite is on an animal; harms it and feeds on it without killing them instantly)
4. Mutualism (both species benefit from each other)
5. Commensalism (one organism benefits, but the other one is neither helped nor harmed)