Final answer:
Symbiosis is a close relationship between organisms of different species in which at least one of the organisms benefits.
Step-by-step explanation:
Symbiosis is a close relationship between organisms of different species in which at least one of the organisms benefits. There are three basic types of symbiosis: mutualism, commensalism, and parasitism. In a mutualistic relationship, both species benefit, in a commensal relationship, one species benefits while the other is neither harmed nor benefited, and in a parasitic relationship, one species benefits while the other is harmed.