There are three basic types of symbiosis. The first type is parasitism in this the host is killed or hurt and the parasite is helped. The second is commensalism in this the host is neither hurt nor helped and the other organism is helped. Then there is mutualism in this the host and the other organism help each other. You can find more information here:
. http://www.marietta.edu/~biol/biomes/symbiosis.htm
